2024-03-28T11:03:27Z
https://lib.jucs.org/oai.php
10.3217/jucs-000-00
1994-11-15
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 0(0): 1-2
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1994
Editorial
text/html
info:doi:10.3217/jucs-000-00
https://doi.org/10.3217/jucs-000-00
https://lib.jucs.org/article/27061/
https://lib.jucs.org/article/27061/download/pdf/
en
10.3217/jucs-000-00-0003
1994-11-15
jucs
Tragic Loss or Good Riddance? The Impending Demise of Traditional Scholarly Journals
Odlyzko,Andrew
JUCS - Journal of Universal Computer Science 0(0): 3-53
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1994
Research Article
text/html
info:doi:10.3217/jucs-000-00-0003
https://doi.org/10.3217/jucs-000-00-0003
https://lib.jucs.org/article/27062/
https://lib.jucs.org/article/27062/download/pdf/
en
10.3217/jucs-000-00-0054
1994-11-15
jucs
Applications and Impact of Hypermedia Systems: An Overview
Lennon,Jennifer
Maurer,Hermann
multimedia
hypermedia
Internet
Hyper-G
hyperlinks
collections
converging technology
e-mail
libraries
electronic publishing
kiosks
CSCW
conferencing
life-long learning
electronic lecture room
CAI
electronic personal assistant.
JUCS - Journal of Universal Computer Science 0(0): 54-107
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1994
Research Article
text/html
info:doi:10.3217/jucs-000-00-0054
https://doi.org/10.3217/jucs-000-00-0054
https://lib.jucs.org/article/27063/
https://lib.jucs.org/article/27063/download/pdf/
en
10.3217/jucs-000-00-0109
1994-11-15
jucs
Journal of Universal Computer Science
Calude,Cristian
Maurer,Hermann
Salomaa,Arto
JUCS - Journal of Universal Computer Science 0(0): 109-116
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1994
Research Article
text/html
info:doi:10.3217/jucs-000-00-0109
https://doi.org/10.3217/jucs-000-00-0109
https://lib.jucs.org/article/27066/
https://lib.jucs.org/article/27066/download/pdf/
en
10.3217/jucs-000-00-0117
1994-11-15
jucs
J.UCS - The Next Generation in Electronic Journal Publishing
Maurer,Hermann
Schmaranz,Klaus
J.UCS
Hyper-G
electronic publishing
electronic journals
JUCS - Journal of Universal Computer Science 0(0): 117-126
In this paper we first discuss briefly why electronic journals today have a rather moderate success. We then describe J.UCS - the Journal of Universal Computer Science - an electronic journal that is the prototype for electronic publishing in the future. Using Hyper-G for distribution it provides all search and navigation mechanisms of large scale hypermedia systems and therefore makes it easy to locate interesting articles. Readers can perform variable scope searches to find papers, then they can browse them on screen either in hypertext mode or in high quality PostScript mode, or they can get high quality PostScript documents for printing. Even PostScript documents provide full hyperlink support when reading them on screen. Articles in J.UCS can be accessed very fast using a wide net of servers distributed all over the world. J.UCS also supports annotations to existing articles informing the readers of new research results or errors. Writing articles for J.UCS is very easy using PostScript as the main submission format, even standard hyperlinks such as literature references are generated automatically. We close this paper with a short comparison of J.UCS to other electronic journals and with an outlook on future developments.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1994
Research Article
text/html
info:doi:10.3217/jucs-000-00-0117
https://doi.org/10.3217/jucs-000-00-0117
https://lib.jucs.org/article/27067/
https://lib.jucs.org/article/27067/download/pdf/
en
10.3217/jucs-000-00-0127
1994-11-15
jucs
On Second Generation Hypermedia Systems
Andrews,Keith
Kappe,Frank
Maurer,Hermann
Schmaranz,Klaus
JUCS - Journal of Universal Computer Science 0(0): 127-136
In this paper we claim that the navigational and structural tools currently available on the Internet are not sufficient to fully exploit the tremendous power of the largest information and communication ressource mankind has ever had. We contend that current hypermedia systems and its most prominent specimen WWW do not have enough functionality to provide the power that is needed. We explain important features that are absent, claim that "second generation" hypermedia systems incorporating such features are essential and mention a first such second generation hypermedia system called Hyper-G, which is just becoming available and is starting to be used for a wide variety of applications.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1994
Research Article
text/html
info:doi:10.3217/jucs-000-00-0127
https://doi.org/10.3217/jucs-000-00-0127
https://lib.jucs.org/article/27074/
https://lib.jucs.org/article/27074/download/pdf/
en
10.3217/jucs-000-00-0137
1994-11-15
jucs
You Believe You Know What Multimedia is? And What Internet Will Do For You? Well ... Think Again!
Lennon,Jennifer
Maurer,Hermann
Converging technology
multimedia
hypermedia
interactive and annotated movies
Internet
Hyper-G.
JUCS - Journal of Universal Computer Science 0(0): 137-143
In the first part of this paper we argue that the terms "multimedia" and "hypermedia" need redefining to reflect latest developments in converging technology. We propose new forms of "interactive" and "annotated" movies, to be created using advanced digital techniques. In the second half of the paper we suggest that some of the problems that users of Internet are currently experiencing are due to "first generation" systems, but that "second generation" answers have already emerged.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1994
Research Article
text/html
info:doi:10.3217/jucs-000-00-0137
https://doi.org/10.3217/jucs-000-00-0137
https://lib.jucs.org/article/27075/
https://lib.jucs.org/article/27075/download/pdf/
en
10.3217/jucs-001-01
1995-01-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(1): 1-1
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-01
https://doi.org/10.3217/jucs-001-01
https://lib.jucs.org/article/27076/
https://lib.jucs.org/article/27076/download/pdf/
en
10.3217/jucs-001-01-0002
1995-01-28
jucs
High-radix Division with Approximate Quotient-digit Estimation
Fenwick,Peter
Division
high radix
approximate digit estimates
JUCS - Journal of Universal Computer Science 1(1): 2-22
High-radix division, developing several quotient bits per clock, is usually limited by the difficulty of generating accurate high-radix quotient digits. This paper describes techniques which allow quotient digits to be inaccurate, but then refine the result. We thereby obtain dividers with slightly reduced performance, but with much simplified logic. For example, a nominal radix-64 divider can generate an average of 4.5 to 5.5 quotient bits per cycle with quite simple digit estimation logic. The paper investigates the technique for radices of 8, 16, 64 and 256, including various qualities of digit estimation, and operation with restricted sets of divisor multiples.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-01-0002
https://doi.org/10.3217/jucs-001-01-0002
https://lib.jucs.org/article/27077/
https://lib.jucs.org/article/27077/download/pdf/
en
10.3217/jucs-001-01-0023
1995-01-28
jucs
On Implementing EREW Work-Optimally on Mesh of Trees
Leppänen,Ville
EREW
mesh of trees
shared memory
simulation
work-optimal
randomized
coated mesh.
JUCS - Journal of Universal Computer Science 1(1): 23-34
We show how to implement an -processor EREW PRAM workoptimally on a 2-dimensional n-sided mesh of trees, consisting of n processors, n memory modules, and nodes. Similarly, we prove that an -processor EREW PRAM can be implemented work-optimally on a 3-dimensional n-sided mesh of trees. By the work-optimality of implementations we mean that the expected routing time of PRAM memory requests is per simulated PRAM processor with high probability. Experiments show that on relatively small and the cost per simulated PRAM processor is 1.5-2.5 in the 2-dimensional case, and 2-3 in the 3-dimensional case. If at each step at most 1/3'th of the PRAM processors make a reference to the shared memory, then the simulation cost is approximately 1. We also compare our work-optimal simulations to those proposed for coated meshes.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-01-0023
https://doi.org/10.3217/jucs-001-01-0023
https://lib.jucs.org/article/27078/
https://lib.jucs.org/article/27078/download/pdf/
en
10.3217/jucs-001-01-0035
1995-01-28
jucs
Levels of Anonymity
Flinn,Bill
Maurer,Hermann
security
anonymous use
access control
authentication
big brother
JUCS - Journal of Universal Computer Science 1(1): 35-47
In this paper we make a first attempt at systematically investigating levels of anonymity required in networked computer systems: we feel it is often overlooked that beyond such obvious cases as identified by means of a password or anonymous use there are many other levels of anonymity, identification and authenticity necessary in various applications.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-01-0035
https://doi.org/10.3217/jucs-001-01-0035
https://lib.jucs.org/article/27080/
https://lib.jucs.org/article/27080/download/pdf/
en
10.3217/jucs-001-01-0048
1995-01-28
jucs
What Is a Random String?
Calude,Cristian S.
Blank-endmarker complexity
Chaitin (self-delimiting) complexity
random strings.
JUCS - Journal of Universal Computer Science 1(1): 48-66
Chaitin s algorithmic definition of random strings - based on the complexity induced by self-delimiting computers - is critically discussed. One shows that Chaitin s model satisfy many natural requirements related to randomness, so it can be considered as an adequate model for finite random objects. It is a better model than the original (Kolmogorov) proposal. Finally, some open problems will be discussed.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-01-0048
https://doi.org/10.3217/jucs-001-01-0048
https://lib.jucs.org/article/27082/
https://lib.jucs.org/article/27082/download/pdf/
en
10.3217/jucs-001-01-0067
1995-01-28
jucs
Grammars Based on the Shuffle Operation
Paun,Gheorghe
Rozenberg,Grzegorz
Salomaa,Arto
Shuffle operation
Chomsky grammars
L Systems
JUCS - Journal of Universal Computer Science 1(1): 67-82
We consider generative mechanisms producing languages by starting from a finite set of words and shuffling the current words with words in given sets, depending on certain conditions. Namely, regular and finite sets are given for controlling the shuffling: strings are shuffled only to strings in associated sets. Six classes of such grammars are considered, with the shuffling being done on a left most position, on a prefix, arbitrarily, globally, in parallel, or using a maximal selector. Most of the corresponding six families of languages, obtained for finite, respectively for regular selection, are found to be incomparable. The relations of these families with Chomsky language families are briefly investigated.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-01-0067
https://doi.org/10.3217/jucs-001-01-0067
https://lib.jucs.org/article/27088/
https://lib.jucs.org/article/27088/download/pdf/
en
10.3217/jucs-001-02
1995-02-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(2): 83-83
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-02
https://doi.org/10.3217/jucs-001-02
https://lib.jucs.org/article/27095/
https://lib.jucs.org/article/27095/download/pdf/
en
10.3217/jucs-001-02-0084
1995-02-28
jucs
A Scalable Architecture for Maintaining Referential Integrity in Distributed Information Systems
Kappe,Frank
Hypertext
Link Consistency
Distributed Information System
Internet
Gopher
WWW
Hyper-G
Scalability
p-flood
JUCS - Journal of Universal Computer Science 1(2): 84-104
One of the problems that we experience with today's most widespread Internet Information Systems (like WWW or Gopher) is the lack of support for maintaining referential integrity. Whenever a resource is (re)moved, dangling references from other resources may occur.This paper presents a scalable architecture for automatic maintenance of referential integrity in large (thousands of servers) distributed information systems. A central feature of the proposed architecture is the p-flood algorithm, which is a scalable, robust, prioritizable, probabilistic server-server protocol for efficient distribution of update information to a large collection of servers.The p-flood algorithm is now implemented in the Hyper-G system, but may in principle also be implemented as an add-on for existing WWW and Gopher servers.Keywords: Hypertext, Link Consistency, Distributed Information System, Internet, Gopher, WWW, Hyper-G, Scalability, p-flood.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-02-0084
https://doi.org/10.3217/jucs-001-02-0084
https://lib.jucs.org/article/27096/
https://lib.jucs.org/article/27096/download/pdf/
en
10.3217/jucs-001-02-0105
1995-02-28
jucs
A Variant of Team Cooperation in Grammar Systems
Freund,Rudolf
Paun,Gheorghe
Formal languages
grammar systems
teams
JUCS - Journal of Universal Computer Science 1(2): 105-130
We prove that grammar systems with (prescribed or free) teams (of constant size at least two or arbitrary size) working as long as they can do, characterize the family of languages generated by (context-free) matrix grammars with appearance checking; in this way, the results in [Paun, Rozenberg 1994] are completed and improved.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-02-0105
https://doi.org/10.3217/jucs-001-02-0105
https://lib.jucs.org/article/27099/
https://lib.jucs.org/article/27099/download/pdf/
en
10.3217/jucs-001-02-0131
1995-02-28
jucs
On Four Classes of Lindenmayerian Power Series
Honkala,Juha
Kuich,Werner
JUCS - Journal of Universal Computer Science 1(2): 131-135
We show that nonzero axioms add to the generative capacity of Lindenmayerian series generating systems. On the other hand, if nonzero axioms are allowed, nonterminals do not, provided that only quasiregular series are considered.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-02-0131
https://doi.org/10.3217/jucs-001-02-0131
https://lib.jucs.org/article/27100/
https://lib.jucs.org/article/27100/download/pdf/
en
10.3217/jucs-001-02-0136
1995-02-28
jucs
The Relationship Between Propagation Characteristics and Nonlinearity of Cryptographic Functions
Seberry,Jennifer
Zhang,Xian-Mo
Zheng,Yuliang
Cryptography
Boolean functions
Encryption functions
Nonlinearity
Propagation Characteristics
SAC
S-boxes
JUCS - Journal of Universal Computer Science 1(2): 136-150
The connections among the various nonlinearity criteria is currently an important topic in the area of designing and analyzing cryptographic functions. In this paper we show a quantitative relationship between propagation characteristics and nonlinearity, two critical indicators of the cryptographic strength of a Boolean function. We also present a tight lower bound on the nonlinearity of a cryptographic function that has propagation characteristics.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-02-0136
https://doi.org/10.3217/jucs-001-02-0136
https://lib.jucs.org/article/27101/
https://lib.jucs.org/article/27101/download/pdf/
en
10.3217/jucs-001-02-0151
1995-02-28
jucs
On Completeness of Pseudosimple Sets
Bulitko,Vadim
Completeness
Pseudosimple set
Effectivization
Extensionally bounded function
JUCS - Journal of Universal Computer Science 1(2): 151-154
The paper contains completeness criterions for pseudosimple sets. Those criterions are constructed using effectivization of the definitions as well as extensionally bounded functions.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-02-0151
https://doi.org/10.3217/jucs-001-02-0151
https://lib.jucs.org/article/27102/
https://lib.jucs.org/article/27102/download/pdf/
en
10.3217/jucs-001-03
1995-03-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(3): 155-155
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-03
https://doi.org/10.3217/jucs-001-03
https://lib.jucs.org/article/27103/
https://lib.jucs.org/article/27103/download/pdf/
en
10.3217/jucs-001-03-0156
1995-03-28
jucs
Combining Concept Mapping and Adaptive Advice to Teach Reading Comprehension
Carlson,Patricia
Larralde,Veronica
JUCS - Journal of Universal Computer Science 1(3): 156-161
When driven by simple models of information processing, reading instruction focuses on basic decoding skills centering on words and sentences. Factoring in advanced cognitive studies adds at least two more dimensions. First, readers must learn a collection of strategies for constructing meaning from text. Second, and most importantly, readers must develop enough situational awareness to diagnose a text and know which strategy to deploy. Teaching intellectual crafts that involve not only base-line performative skills but also a repertoire of problem-solving heuristics, and the metacognitive maturity to orchestrate multi-leveled activities, works well in a master-apprentice model. However, one-on-one instruction is far too labor-intensive to be commonplace in the teaching of reading. This paper describes a computerized learning environment for teaching the conceptual patterns of critical literacy. While the full implementation of the software treats both reading and writing, this paper covers only the reading aspects of R-WISE (Reading and Writing in a Supportive Environment).
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-03-0156
https://doi.org/10.3217/jucs-001-03-0156
https://lib.jucs.org/article/27104/
https://lib.jucs.org/article/27104/download/pdf/
en
10.3217/jucs-001-03-0162
1995-03-28
jucs
Modular Range Reduction
Daumas,Marc
Mazenc,Christophe
Merrheim,Xavier
Muller,Jean-Michel
Computer Arithmetic
Elementary Functions
Range Reduction
JUCS - Journal of Universal Computer Science 1(3): 162-175
A new range reduction algorithm, called ModularRange Reduction (MRR), briefly introduced by the authors in [Daumas et al. 1994] is deeply analyzed. It is used to reduce the arguments to exponential and trigonometric function algorithms to be within the small range for which the algorithms are valid. MRR reduces the arguments quickly and accurately. A fast hardwired implementation of MRR operates in time (log(n)), where n is the number of bits of the binary input value. For example, with MRR it becomes possible to compute the sine and cosine of a very large number accurately. Web propose two possible architectures implementing this algorithm.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-03-0162
https://doi.org/10.3217/jucs-001-03-0162
https://lib.jucs.org/article/27105/
https://lib.jucs.org/article/27105/download/pdf/
en
10.3217/jucs-001-03-0176
1995-03-28
jucs
Special Cases of Division
Doran,R.
JUCS - Journal of Universal Computer Science 1(3): 176-194
This surveys algorithms and circuits for integer division in special cases. These include division by constants, small divisors, exact divisors, and cases where the divisor and the number base have a special relationship. The related operation of remainder is also covered. Various prior techniques are treated in a common framework. Worked examples are provided together with examples of practical application.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-03-0176
https://doi.org/10.3217/jucs-001-03-0176
https://lib.jucs.org/article/27106/
https://lib.jucs.org/article/27106/download/pdf/
en
10.3217/jucs-001-03-0195
1995-03-28
jucs
Bringing ITS to the Marketplace: A Successful Experiment in Minimalist Design
Gutwin,Carl
Jones,Marlene
Brackett,Patrick
Adolphe,Kim
JUCS - Journal of Universal Computer Science 1(3): 195-200
Intelligent Tutoring Systems (ITS) have proven to be effective tools for teaching and training. However, ITSs have not become common in industrial and organisational settings, in part because their complexity has proven difficult to manage outside of the research lab. Minimalist ITSs are an attempt to bridge the gap between research and practical application, they simplify research techniques while striving to maintain as much pedagogic intelligence as possible. This paper describes one such system, SWIFT, that is an example of how a minimalist ITS can be delivered as a commercial product. We outline some of the issues facing designers of a minimalist system, and describe the ways that research techniques have been incorporated into four modules of SWIFT: adaptive testing, course planning, guidance, and diagnosis.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-03-0195
https://doi.org/10.3217/jucs-001-03-0195
https://lib.jucs.org/article/27109/
https://lib.jucs.org/article/27109/download/pdf/
en
10.3217/jucs-001-03-0201
1995-03-28
jucs
Halting Probability Amplitude of Quantum Computers
Svozil,Karl
JUCS - Journal of Universal Computer Science 1(3): 201-204
The classical halting probability introduced by Chaitin is generalized to quantum computations. (The quantum omega was invented in a meeting of G. Chaitin, A. Zeilinger and the author (K. S.) in a Viennese coffee house (Cafe Braeunerhof) in January 1991. Thus, the group should be credited for the original invention, whereas any blame should remain with the author.)
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-03-0201
https://doi.org/10.3217/jucs-001-03-0201
https://lib.jucs.org/article/27112/
https://lib.jucs.org/article/27112/download/pdf/
en
10.3217/jucs-001-04
1995-04-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(4): 205-205
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-04
https://doi.org/10.3217/jucs-001-04
https://lib.jucs.org/article/27113/
https://lib.jucs.org/article/27113/download/pdf/
en
10.3217/jucs-001-04-0206
1995-04-28
jucs
The Hyper-G Network Information System
Andrews,Keith
Kappe,Frank
Maurer,Hermann
Hypermedia
information system
information visualisation
graphical interaction
Internet
JUCS - Journal of Universal Computer Science 1(4): 206-220
As the Internet continues to experience exponential rates of growth, attention is shifting away from mainstream network services such as electronic mail and file transfer to more interactive information services. Current network information systems, whilst extremely successful, run into problems of fragmentation, consistency, scalability, and loss of orientation.The development of 'second generation' network information systems such as Hyper-G can help overcome these limitations. Of particular note are Hyper-Gs tightly-coupled structuring, linking, and search facilities, its projection of a seamless information space across server boundaries with respect to each of these facilities, and its support for multiple languages. The Harmony client for Hyper-G utilises two and three-dimensional visualisations of the information space and couples location feedback to search and link browsing operations, in order to reduce the likelihood of disorientation. This paper presents a comprehensive overview of Hyper-G and Harmony.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-04-0206
https://doi.org/10.3217/jucs-001-04-0206
https://lib.jucs.org/article/27114/
https://lib.jucs.org/article/27114/download/pdf/
en
10.3217/jucs-001-04-0221
1995-04-28
jucs
About WWW
Cailliau,R.
WWW
World-Wide Web
History
SGML
cultural Aspects
Society.
JUCS - Journal of Universal Computer Science 1(4): 221-231
The World-Wide Web is the most talked-about distributed information system today. This paper does not touch on its workings, it tries to give a brief history and outlines the feelings provoked by the explosive adoption in all circles of WWW as the first vehicle on the Global Information Infrastructure.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-04-0221
https://doi.org/10.3217/jucs-001-04-0221
https://lib.jucs.org/article/27115/
https://lib.jucs.org/article/27115/download/pdf/
en
10.3217/jucs-001-04-0232
1995-04-28
jucs
Electronic Publishing
Götze,Dietrich
JUCS - Journal of Universal Computer Science 1(4): 232-234
Publishing the results of scientific research is the basis of the advancement of science, technology and medicine.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-04-0232
https://doi.org/10.3217/jucs-001-04-0232
https://lib.jucs.org/article/27116/
https://lib.jucs.org/article/27116/download/pdf/
en
10.3217/jucs-001-04-0235
1995-04-28
jucs
Evolution of Internet Gopher
Mccahill,Mark
Anklesaria,Farhad
Distributed Information Systems
Internet Gopher
Gopher+
JUCS - Journal of Universal Computer Science 1(4): 235-246
How the Internet Gopher system has evolved since its first released in 1991 and how Internet Gopher relates to other popular Internet information systems. Current problems and future directions for the Internet Gopher system.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-04-0235
https://doi.org/10.3217/jucs-001-04-0235
https://lib.jucs.org/article/27118/
https://lib.jucs.org/article/27118/download/pdf/
en
10.3217/jucs-001-04-0247
1995-04-28
jucs
WAIS and Information Retrieval on the Internet
Mülner,Helmut
JUCS - Journal of Universal Computer Science 1(4): 247-250
WAIS (Wide Area Information Servers), a development of Thinking Machine Corporation, turned out to be one of the main search engines in connection with the World Wide Web (WWW). This article gives a short overview of WAIS, its history, its basics and some connected developments.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-04-0247
https://doi.org/10.3217/jucs-001-04-0247
https://lib.jucs.org/article/27122/
https://lib.jucs.org/article/27122/download/pdf/
en
10.3217/jucs-001-05
1995-05-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(5): 251-251
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-05
https://doi.org/10.3217/jucs-001-05
https://lib.jucs.org/article/27123/
https://lib.jucs.org/article/27123/download/pdf/
en
10.3217/jucs-001-05-0252
1995-05-28
jucs
Conditional Tabled Eco-Grammar Systems
Csuhaj-Varju,Erzsebet
Paun,Gheorghe
Salomaa,Arto
Grammar systems
L systems
Artificial Life
JUCS - Journal of Universal Computer Science 1(5): 252-268
We investigate the generative capacity of the so-called conditional tabled eco-grammar systems (CTEG). They are a variant of ecogrammar systems, generative mechanisms recently introduced as models of the interplay between environment and agents in eco-systems. In particular, we compare the power of CTEG systems with that of programmed and of random context T0L systems and with that of ET0L systems. CTEG systems with one agent only (and without extended symbols) are found to be surprisingly powerful (they can generate non-ET0L languages). Representation theorems for ET0L and for recursively enumerable languages in terms of CTEG languages are also presented. 1.) Research supported by the Academy of Finland, Project 11281
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-05-0252
https://doi.org/10.3217/jucs-001-05-0252
https://lib.jucs.org/article/27124/
https://lib.jucs.org/article/27124/download/pdf/
en
10.3217/jucs-001-05-0269
1995-05-28
jucs
HOME: An Environment for Hypermedia Objects
Duval,Erik
Olivié,Henk
Hanlon,Piers
Jameson,David
HOME
distributed hypermedia
networked multimedia
image store
navigation
query
JUCS - Journal of Universal Computer Science 1(5): 269-291
In this paper, we present HOME, a new environment for distributed hypermedia. We mainly concentrate on the server side, and provide access to World-Wide Web clients through a gateway mechanism. Data and metadata are strictly separated in the distributed HOME server. The architecture is based on a layered approach with separate layers for raw data, multimedia characteristics and hypermedia structure. We briefly present some of the implementation aspects and emphasise distinctive characteristics of HOME. We conclude with a comparison with related research and our plans for the future.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-05-0269
https://doi.org/10.3217/jucs-001-05-0269
https://lib.jucs.org/article/27125/
https://lib.jucs.org/article/27125/download/pdf/
en
10.3217/jucs-001-05-0292
1995-05-28
jucs
Lexical Analysis with a Simple Finite-Fuzzy-Automaton Model
Mateescu,Alexandru
Salomaa,Arto
Salomaa,Kai
Yu,Sheng
JUCS - Journal of Universal Computer Science 1(5): 292-311
Many fuzzy automaton models have been introduced in the past. Here, we discuss two basic finite fuzzy automaton models, the Mealy and Moore types, for lexical analysis. We show that there is a remarkable difference between the two types. We consider that the latter is a suitable model for implementing lexical analysers. Various properties of fuzzy regular languages are reviewed and studied. A fuzzy lexical analyzer generator (FLEX) is proposed. 1.) The work reported here has been supported by the Natural Sciences and Engineering Research Council of Canada grants OGP0041630 and the Project 11281 of the Academy of Finland.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-05-0292
https://doi.org/10.3217/jucs-001-05-0292
https://lib.jucs.org/article/27126/
https://lib.jucs.org/article/27126/download/pdf/
en
10.3217/jucs-001-05-0312
1995-05-28
jucs
Software Patents and The Internet
Shearer,Jenny
Vermeer,Arnould
Software patents
debate
Internet
Compuserve
Unisys
LZW GIF
JUCS - Journal of Universal Computer Science 1(5): 312-319
The attempt by Unisys to obtain royalties from the Lempel Zev Welch Graphics Interchange Format specification through Compuserve has wide implications for the Internet. Increased activity in the US software patents area is likely to result in damage to progress of the software arts and the Internet, and to generate upscaled protest from Internet users. The LZW GIF case highlights the Internet culture in favour of free and unfettered development. Clarification of this important principle will have a major effect on the future of the Internet.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-05-0312
https://doi.org/10.3217/jucs-001-05-0312
https://lib.jucs.org/article/27127/
https://lib.jucs.org/article/27127/download/pdf/
en
10.3217/jucs-001-05-0320
1995-05-28
jucs
GAC - the Criterion for Global Avalanche Characteristics of Cryptographic Functions
Zhang,Xian-Mo
Zheng,Yuliang
JUCS - Journal of Universal Computer Science 1(5): 320-337
We show that some widely accepted criteria for cryptographic functions, including the strict avalanche criterion (SAC) and the propagation criterion, have various limitations in capturing properties of vital importance to cryptographic algorithms, and propose a new criterion called GAC to measure the global avalanche characteristics of cryptographic functions. We also introduce two indicators related to the new criterion, one forecasts the sum-of-squares while the other the absolute avalanche characterist- ics of a function. Lower and upper bounds on the two indicators are derived, and two methods are presented to construct cryptographic functions that achieve nearly optimal global avalanche characteristics.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-05-0320
https://doi.org/10.3217/jucs-001-05-0320
https://lib.jucs.org/article/27128/
https://lib.jucs.org/article/27128/download/pdf/
en
10.3217/jucs-001-06
1995-06-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(6): 338-338
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-06
https://doi.org/10.3217/jucs-001-06
https://lib.jucs.org/article/27129/
https://lib.jucs.org/article/27129/download/pdf/
en
10.3217/jucs-001-06-0339
1995-06-28
jucs
A Translation of the Pi-Calculus Into MONSTR
Banach,Richard
Balázs,J.
Papadopoulos,George
Concurrency
Pi-Calculus
Term Graph Rewriting
MONSTR
Process Networks
Simulation
Serialisability.
JUCS - Journal of Universal Computer Science 1(6): 339-398
A translation of the pi-calculus into the MONSTR graph rewriting language is described and proved correct. The translation illustrates the heavy cost in practice of faithfully implementing the communication primitive of the pi-calculus and similar process calculi. It also illustrates the convenience of representing an evolving network of communicating agents directly within a graph manipulation formalism, both because the necessity to use delicate notions of bound variables and of scopes is avoided, and also because the standard model of graphs in set theory automatically yields a useful semantics for the process calculus. The correctness proof illustrates many features typically encountered in reasoning about graph rewriting systems, and particularly how serialisation techniques can be used to reorder an arbitrary execution into one having stated desirable properties.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-06-0339
https://doi.org/10.3217/jucs-001-06-0339
https://lib.jucs.org/article/27130/
https://lib.jucs.org/article/27130/download/pdf/
en
10.3217/jucs-001-06-0399
1995-06-28
jucs
Distributed Caching in Networked File Systems
Klauser,Artur
Posch,Reinhard
networked file systems
distributed file caches
load balancing
file system performance
JUCS - Journal of Universal Computer Science 1(6): 399-409
Changing relative performance of processors, networks, and disks makes it necessary to reconsider algorithms using these three resources. As networks get faster and less congested topologies emerge, it becomes important to use network resources more aggressively to obtain good performance. Substitution of local disk accesses by accesses to remote memory can lead to better balanced resource usage and thus to faster systems. In this work we address the issue of file caching in a networked file system configuration. Distributed block-level in-memory caches are considered. We show that carefully constructed distributed concepts can lead to lower server load and better overall system performance than centralized concepts. Oversimplification, although aimed at gaining performance for single components, may deteriorate overall performance as a result of unbalanced resource usage.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-06-0399
https://doi.org/10.3217/jucs-001-06-0399
https://lib.jucs.org/article/27131/
https://lib.jucs.org/article/27131/download/pdf/
en
10.3217/jucs-001-06-0410
1995-06-28
jucs
From Personal Computer to Personal Assistant
Lennon,Jennifer
Vermeer,Arnould
Electronic assistants
electronic agents
message pads
searches
prediction
programming by example
voice commands.
JUCS - Journal of Universal Computer Science 1(6): 410-422
Much of the confusion that surrounds electronic personal assistants arises from the open-ended complexity of their development. In this paper we categorise some of their more common uses before suggesting several thought-provoking extensions.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-06-0410
https://doi.org/10.3217/jucs-001-06-0410
https://lib.jucs.org/article/27132/
https://lib.jucs.org/article/27132/download/pdf/
en
10.3217/jucs-001-06-0423
1995-06-28
jucs
Microworlds For Teaching Concepts of Object Oriented Programming
Tomek,Ivan
Microworld
object oriented programming
progressive disclosure
Smalltalk
teaching object oriented programming
computer literacy.
JUCS - Journal of Universal Computer Science 1(6): 423-434
We present two examples of microworlds built into the Smalltalk environment for the purpose of teaching the main concepts of object oriented programming (OOP) and of the Smalltalk programming language. Thee distinguishing features of our microworlds are that each of them presents the student with a sequence of environments. These environments introduce one OOP concept after another, and disclose the Smalltalk environment and language in a step-by-step fashion. The starting environment does not require any programming and does not encourage the user to use Smalltalk tools, the last environment must be programmed in Smalltalk and discloses the major Smalltalk tools. The intended use of our microworlds is for the introductory part of a course on OOP, to be followed by a detailed presentation of the language. An extension of the presented approach would make the method suitable for teaching basics of computer programming in a computer literacy course.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-06-0423
https://doi.org/10.3217/jucs-001-06-0423
https://lib.jucs.org/article/27133/
https://lib.jucs.org/article/27133/download/pdf/
en
10.3217/jucs-001-07
1995-07-28
jucs
Managing Editor's Column
Maurer,Hermann
Bajard,Jean-Claude
Michelucci,Dominique
Moreau,Jean-Michel
Muller,Jean-Michel
JUCS - Journal of Universal Computer Science 1(7): 435-438
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-07
https://doi.org/10.3217/jucs-001-07
https://lib.jucs.org/article/27136/
https://lib.jucs.org/article/27136/download/pdf/
en
10.3217/jucs-001-07-0439
1995-07-28
jucs
A High Radix On-line Arithmetic for Credible and Accurate Computing
Lynch,Thomas
Schulte,Michael
High-radix
on-line arithmetic
precision
accurate
reliable
credible
super-scaler
VLIW.
JUCS - Journal of Universal Computer Science 1(7): 439-453
The result of a simple floating-point computation can be in great error, even though no error is signaled, no coding mistakes are in the program, and the computer hardware is functioning correctly. This paper proposes a set of instructions appropriate for a general purpose microprocessor that can be used to improve the credibility and accuracy of numerical computations. Such instructions provide direct hardware support for monitoring events which may threaten computational integrity, implementing floating-point data types of arbitrary precision, and repeating calculations with greater precision. These useful features are obtained by the efficient implementation of high radix on-line arithmetic. The prevalence of super-scalar and VLIW processors makes this approach especially attractive.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0439
https://doi.org/10.3217/jucs-001-07-0439
https://lib.jucs.org/article/27137/
https://lib.jucs.org/article/27137/download/pdf/
en
10.3217/jucs-001-07-0454
1995-07-28
jucs
Estimation of Round-off Errors on Several Computers Architectures
Asserrhine,Jalil
Chesneaux,Jean-Marie
Lamotte,Jean-Luc
JUCS - Journal of Universal Computer Science 1(7): 454-468
Numerical validation of computed results in scientific computation is always an essential problem as well on sequential architecture as on parallel architecture. The probabilistic approach is the only one that allows to estimate the round-off error propagation of the floating point arithmetic on computers. We begin by recalling the basics of the CESTAC method (Controle et Estimation Stochastique des Arrondis de Calculs). Then, the use of the CADNA software (Control of Accuracy and Debugging For Numerical Applications) is presented for numerical validation on sequential architecture. On parallel architecture, we present two solutions for the control of round-off errors. The first one is the combination of CADNA and the PVM library. This solution allows to control round-off errors of parallel codes with the same architecture. It does not need more processors than the classical parallel code. The second solution is represented by the RAPP prototype. In this approach, the CESTAC method is directly parallelized. It works both on sequential and parallel programs. The essential difference is that this solution requires more processors than the classical codes. These different approaches are tested on sequential and parallel programs of multiplication of matrices.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0454
https://doi.org/10.3217/jucs-001-07-0454
https://lib.jucs.org/article/27138/
https://lib.jucs.org/article/27138/download/pdf/
en
10.3217/jucs-001-07-0469
1995-07-28
jucs
Round-off Error Propagation in the Solution of the Heat Equation by finite Differences
Jézéquel,Fabienne
Floating point arithmetic
numerical error propagation
partial differential equations
finite difference methods
JUCS - Journal of Universal Computer Science 1(7): 469-483
The effect of round-off errors on the numerical solution of the heat equation by finite differences can be theoretically determined by computing the mean error at each time step. The floating point error propagation is then theoretically time linear. The experimental simulations agree with this result for the towards zero rounding arithmetic. However the results are not so good for the rounding to the nearest artihmetic. The theoretical formulas provide an approximation of the experimental round-off errors. In these formulas the mean value of the assignment operator is used, and consequently, their reliability depends on the arithmetic used.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0469
https://doi.org/10.3217/jucs-001-07-0469
https://lib.jucs.org/article/27140/
https://lib.jucs.org/article/27140/download/pdf/
en
10.3217/jucs-001-07-0484
1995-07-28
jucs
LCF: A Lexicographic Binary Representation of the Rationals
Kornerup,Peter
Matula,David
Computer arithmetic
continued fractions
lexicographic
number systems
number theory
rational numbers.
JUCS - Journal of Universal Computer Science 1(7): 484-503
A binary representation of the rationals derived from their continued fraction expansions is described and analysed. The concepts "adjacency", "mediant" and "convergent" from the literature on Farey fractions and continued fractions are suitably extended to provide a foundation for this new binary representation system. Worst case representation-induced precision loss for any real number by a fixed length representable number of the system is shown to be at most 19% of bit word length, with no precision loss whatsoever induced in the representation of any reasonably sized rational number. The representation is supported by a computer arithmetic system implementing exact rational and approximate real computations in an on-line fashion.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0484
https://doi.org/10.3217/jucs-001-07-0484
https://lib.jucs.org/article/27141/
https://lib.jucs.org/article/27141/download/pdf/
en
10.3217/jucs-001-07-0504
1995-07-28
jucs
Exact Statistics and Continued Fractions
Lester,David
JUCS - Journal of Universal Computer Science 1(7): 504-513
In this paper we investigate an extension to Vuillemin's work on continued fraction arithmetic [Vuillemin 87, Vuillemin 88, Vuillemin 90], that permits it to evaluate the standard statistical distribution functions. By this we mean: the normal distribution, the -distribution, the t-distribution, and, in particular, the F-distribution. The underlying representation of non-rational computable real numbers is also as continued fractions, in the style of Vuillemin. This permits arbitrary accuracy over a range of values. The number of terms of a continued fraction that are used by the implementation is dynamically controlled by the accuracy demanded of the final answer. The use of a modern lazy functional language - Haskell - has considerably eased the programming task. Two features are of note. Firstly, the type-class structure allows one to augment the varieties of numbers supported by the language. Secondly, the laziness inherent in the Haskell's semantics, makes it very straightforward to dynamically control the accuracy of the intermediate evaluations.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0504
https://doi.org/10.3217/jucs-001-07-0504
https://lib.jucs.org/article/27143/
https://lib.jucs.org/article/27143/download/pdf/
en
10.3217/jucs-001-07-0514
1995-07-28
jucs
On Directed Interval Arithmetic and its Applications
Markov,Svetoslav
computer arithmetic
error analysis
interval algebraic manipulation
JUCS - Journal of Universal Computer Science 1(7): 514-526
We discuss two closely related interval arithmetic systems: i) the of directed (generalized) intervals studied by E. Kaucher, and ii) the syste intervals together with the outer and inner interval operations. A relation two systems becomes feasible due to introduction of special notations and a normal form of directed intervals. As an application, it has been shown that interval systems can be used for the computation of tight inner and outer in of ranges of functions and consequently for the development of software for computation of ranges of functions.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0514
https://doi.org/10.3217/jucs-001-07-0514
https://lib.jucs.org/article/27145/
https://lib.jucs.org/article/27145/download/pdf/
en
10.3217/jucs-001-07-0527
1995-07-28
jucs
MSB-First Digit Serial Arithmetic
Nielsen,Asger
Kornerup,Peter
Computer Arithmetic
On-line Computation
Number Representations
Redundant Digit sets
Continued Fractions
Intervals
JUCS - Journal of Universal Computer Science 1(7): 527-547
We develop a formal account of digit serial number representations by describing them as strings from a language. A prefix of a string represents an int erval approximating a number by enclosure. Standard on-line representations are shown to be a special case of the general digit serial representations. Matrices are introd uced as representations of intervals and a finite-state transducer is used for mapping str ings into intervals. Homographic and bi-homographic functions are used for representing basi c arithmetic operations on digit serial numbers, and finally a digit serial represen tation of floating point numbers is introduced. 1.) This work has been supported by The Danish Research Councils under the grant no.5.21.08.02.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0527
https://doi.org/10.3217/jucs-001-07-0527
https://lib.jucs.org/article/27146/
https://lib.jucs.org/article/27146/download/pdf/
en
10.3217/jucs-001-07-0548
1995-07-28
jucs
Some Algorithms Providing Rigorous Bounds for the Eigenvalues of a Matrix
Pavec,Raymond
JUCS - Journal of Universal Computer Science 1(7): 548-559
Three algorithms providing rigourous bounds for the eigenvalues of a real matrix are presented. The first is an implementation of the bisection algorithm for a symmetric tridiagonal matrix using IEEE floating-point arithmetic. The two others use interval arithmetic with directed rounding and are deduced from the Jacobi method for a symmetric matrix and the Jacobi-like method of Eberlein for an unsymmetric matrix.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0548
https://doi.org/10.3217/jucs-001-07-0548
https://lib.jucs.org/article/27147/
https://lib.jucs.org/article/27147/download/pdf/
en
10.3217/jucs-001-07-0560
1995-07-28
jucs
On a Formally Correct Implementation of IEEE Computer Arithmetic
Popova,Evgenija
computer arithmetic
implementation
IEEE standards
exception handling
JUCS - Journal of Universal Computer Science 1(7): 560-569
IEEE floating-point arithmetic standards 754 and 854 reflect the present state of the art in designing and implementing floating-point arithmetic units. A formalism applied to a standard non-trapping mode floating-point system shows incorrectness of some numeric and non-numeric results. A software emulation of decimal floating-point computer arithmetic supporting an enhanced set of exception symbols is reported. Some implementation details, discussion of some open questions about utility and consistency of the implemented arithmetic with the IEEE Standards are provided. The potential benefit for computations with infinite symbolic elements is outlined.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-07-0560
https://doi.org/10.3217/jucs-001-07-0560
https://lib.jucs.org/article/27148/
https://lib.jucs.org/article/27148/download/pdf/
en
10.3217/jucs-001-08
1995-08-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(8): 570-570
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-08
https://doi.org/10.3217/jucs-001-08
https://lib.jucs.org/article/27150/
https://lib.jucs.org/article/27150/download/pdf/
en
10.3217/jucs-001-08-0571
1995-08-28
jucs
BROCA : A Computerized Environment for Mediating Scientific Reasoning through Writing
Carlson,Patricia
Computers and Education
Computer Uses in Education
JUCS - Journal of Universal Computer Science 1(8): 571-590
This paper describes a work-in-progress: a computerized learning environment for teaching the conceptual patterns of scientific reasoning. BROCA (Basic Research, Observations, Critical Analysis) is theory-driven, combining two very powerful conceptual models of thinking. The first -- drawn from cognitive psychology and information theory -- focuses on the mental manipulations by which data becomes information and information becomes knowledge. The second theoretical construct comes from rhetoric and describes the intellectual activities carried out in prewriting, drafting, and revision by an expert writing. As an interactive "cognitive tool," BROCA provides scaffolding (through visual algorithms and adaptive prompting) to help a fledgling thinker practice the robust patterns of scientific reasoning.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-08-0571
https://doi.org/10.3217/jucs-001-08-0571
https://lib.jucs.org/article/27151/
https://lib.jucs.org/article/27151/download/pdf/
en
10.3217/jucs-001-08-0591
1995-08-28
jucs
Differential Ziv-Lempel Text Compression
Fenwick,Peter
text compression
LZ-77
arithmetic coding
vector quantisation
JUCS - Journal of Universal Computer Science 1(8): 591-602
We describe a novel text compressor which combines Ziv-Lempel compression and arithmetic coding with a form of vector quantisation. The resulting compressor resembles an LZ-77 compressor, but with no explicit phrase lengths or coding for literans. An examination of the limitations on its performance leads to some predictions of the limits of LZ-77 compression in general, showing that the LZ-77 text compression technique is already very close to the limits of its performance.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-08-0591
https://doi.org/10.3217/jucs-001-08-0591
https://lib.jucs.org/article/27152/
https://lib.jucs.org/article/27152/download/pdf/
en
10.3217/jucs-001-08-0603
1995-08-28
jucs
Bounds for Heights of Integer Polynomial Factors
Panaitopol,Laurentiu
Ştefănescu,Doru
JUCS - Journal of Universal Computer Science 1(8): 603-613
We describe new methods for the estimation of the bounds of the coefficients of proper divisors of integer polynomials in one variable. There exist classes of poly-nomials for which our estimates are better than those obtained using the polynomial measure or the 2-weighted norm.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-08-0603
https://doi.org/10.3217/jucs-001-08-0603
https://lib.jucs.org/article/27153/
https://lib.jucs.org/article/27153/download/pdf/
en
10.3217/jucs-001-08-0614
1995-08-28
jucs
A Robust Affine Matching Algorithm Using an Exponentially Decreasing Distance Function
Pinz,Axel
Prantl,Manfred
Ganster,Harald
Affine Matching
Spatial Registration
Information Fusion
Image Understanding
JUCS - Journal of Universal Computer Science 1(8): 614-631
We describe a robust method for spatial registration, which relies on the coarse correspondence of structures extracted from images, avoiding the establishment of point correspondences. These structures (tokens) are points, chains, polygons and regions at the level of intermediate symbolic representation (ISR). The algorithm recovers conformal transformations (4 affine parameters), so that 2-dimensional scenes as well as planar structures in 3D scenes can be handled. The affine transformation between two different tokensets is found by minimization of an exponentially decreasing distance function. As long as the tokensets are kept sparse, the method is very robust against a broad variety of common disturbances (e.g. incomplete segmentations, missing tokens, partial overlap). The performance of the algorithm is demonstrated using simple 2D shapes, medical, and remote sensing satellite images. The complexity of the algorithm is quadratic on the number of affine parameters.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-08-0614
https://doi.org/10.3217/jucs-001-08-0614
https://lib.jucs.org/article/27154/
https://lib.jucs.org/article/27154/download/pdf/
en
10.3217/jucs-001-09
1995-09-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(9): 632-632
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-09
https://doi.org/10.3217/jucs-001-09
https://lib.jucs.org/article/27157/
https://lib.jucs.org/article/27157/download/pdf/
en
10.3217/jucs-001-09-0633
1995-09-28
jucs
An Efficient Distributed Algorithm For st-numbering the Vertices of a Biconnected Graph
Aranha,R. F. M.
Rangan,C.
Distributed graph algorithms
st-numbering
biconnected graph
JUCS - Journal of Universal Computer Science 1(9): 633-651
Given a biconnected network G with n nodes and a specific edge (r, s) of G, the st-numbering problem asks for an assignment of integers to the nodes satisfying the following condition: r is assigned the number 1 and s is assigned the number n and all other nodes are assigned numbers in such a way that every node (other than r and s) has a neighbour with smaller st-number and a neighbour with larger st-number. Since st-numbering exists iff G is biconnected, it serves as a powerful "local characterization" of the "global" property of the network. We present an efficient O(e) message complexity and O(n) time complexity algorithm for st-numbering a biconnected graph.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-09-0633
https://doi.org/10.3217/jucs-001-09-0633
https://lib.jucs.org/article/27158/
https://lib.jucs.org/article/27158/download/pdf/
en
10.3217/jucs-001-09-0652
1995-09-28
jucs
A Decision Method for the Unambiguity of Sets Defined by Number Systems
Honkala,Juha
JUCS - Journal of Universal Computer Science 1(9): 652-657
We show that it is decidable, given a number system N, whether or not there is an unambiguous number system equivalent to N.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-09-0652
https://doi.org/10.3217/jucs-001-09-0652
https://lib.jucs.org/article/27163/
https://lib.jucs.org/article/27163/download/pdf/
en
10.3217/jucs-001-09-0658
1995-09-28
jucs
A Method for Proving Theorems in Differential Geometry and Mechanics
Wang,Dongming
Differential geometry
mechanics
polynomial elimination
theorem proving
triangular system
zero decomposition
JUCS - Journal of Universal Computer Science 1(9): 658-673
A zero decomposition algorithm is presented and used to devise a method for proving theorems automatically in differential geometry and mechanics. The method has been implemented and its practical efficiency is demonstrated by several non-trivial examples including Bertrand s theorem, Schell s theorem and Kepler-Newton s laws.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-09-0658
https://doi.org/10.3217/jucs-001-09-0658
https://lib.jucs.org/article/27164/
https://lib.jucs.org/article/27164/download/pdf/
en
10.3217/jucs-001-10
1995-10-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(10): 674-674
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-10
https://doi.org/10.3217/jucs-001-10
https://lib.jucs.org/article/27165/
https://lib.jucs.org/article/27165/download/pdf/
en
10.3217/jucs-001-10-0675
1995-10-28
jucs
An Aperiodic Set of Wang Cubes
Ii.,Karel
Kari,Jarkko
discrete mathematics
automata theory
aperiodic tilings
Wang tiles
Wang cubes
sequential machines
JUCS - Journal of Universal Computer Science 1(10): 675-686
We introduce Wang cubes with colored faces that are a generalization of Wang tiles with colored edges. We show that there exists an aperiodic set of 21 Wang cubes, that is, a set for which there exists a tiling of the whole space with matching unit cubes but there exists no periodic tiling. We use the aperiodic set of 13 Wang tiles recently obtained by the first author using the new method developed by the second. Our method can be used to construct an aperiodic set of n-dimensional cubes for any n 3.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-10-0675
https://doi.org/10.3217/jucs-001-10-0675
https://lib.jucs.org/article/27167/
https://lib.jucs.org/article/27167/download/pdf/
en
10.3217/jucs-001-10-0687
1995-10-28
jucs
Contained Hypermedia
Duval,Erik
Olivié,Henk
Scherbakov,Nick
hypermedia data modeling
automatic link maintenance
JUCS - Journal of Universal Computer Science 1(10): 687-705
We propose a new hypermedia data model, called CHM for Contained HyperMedia. Our model is based on set-oriented data structuring, with a strong emphasis on automatic maintenance of link integrity. In this paper, the CHM model is presented in detail: both data structuring, navigational facilities and authoring support are presented. We will also explain how we have integrated support for the CHM model in Home, our Hypermedia Object Management Environment, publicly accessible through the World-Wide Web.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-10-0687
https://doi.org/10.3217/jucs-001-10-0687
https://lib.jucs.org/article/27170/
https://lib.jucs.org/article/27170/download/pdf/
en
10.3217/jucs-001-10-0706
1995-10-28
jucs
Authoring on the Fly
Ottmann,Thomas
Bacher,Ch.
electronic courseware
hypermedia
whiteboard
distance teaching
JUCS - Journal of Universal Computer Science 1(10): 706-717
We report about a new way of producing hypermedia documents for supporting teaching at universities. A computer held lecture is automatically converted into the core of a multimedia document and linked together with papers, textbooks, animations and simulations. As an electronic substitute of the blackboard we have used the whiteboard wb of the Mbone toolset and have transmitted the lecture also to remote locations. Our experiments demonstrate that classroom lecturing, distance teaching, and the production of educational hypermedia can be successfully integrated.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-10-0706
https://doi.org/10.3217/jucs-001-10-0706
https://lib.jucs.org/article/27174/
https://lib.jucs.org/article/27174/download/pdf/
en
10.3217/jucs-001-11
1995-11-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(11): 718-718
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-11
https://doi.org/10.3217/jucs-001-11
https://lib.jucs.org/article/27179/
https://lib.jucs.org/article/27179/download/pdf/
en
10.3217/jucs-001-11-0719
1995-11-28
jucs
Digital Libraries as Learning and Teaching Support
Maurer,Hermann
Lennon,Jennifer
Digital libraries
electronic libraries
learning support
teaching support
instructional technology
CAI
CBT
JUCS - Journal of Universal Computer Science 1(11): 719-727
For 30 years repeated attempts have been made to use computers to support the teaching and learning process, albeit with only moderate success. Whenever major attempts failed, some seemingly convincing reasons were presented the for less than satisfactory results. In the early days cost or even lack of suitable equipment was blamed, after colour graphics computers started to be widespread, production costs of interactive and graphically appealing material were considered the main culprits, when modern multimedia authoring techniques did not change the situation either, the lack of personalized feed-back, of network support and the difficulty of producing high quality simulations were seen as main obstacles. With networks now offering excellent multimedia presentation and communication facilities the final breakthrough of computers as ultimate teaching and learning tool is (once more) predicted. And once more results will be disappointing if one crucial component is again overlooked: good courseware must give both guidance to students but also provide a rich variety of background material whenever such is needed. It is the main claim of this paper that the advent of sizeable digital libraries provides one of the most significant chances for computer based training ever. We will argue that such libraries not only allow the efficient production of courseware but also provide the extensive background reservoir of material needed in many situations.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-11-0719
https://doi.org/10.3217/jucs-001-11-0719
https://lib.jucs.org/article/27180/
https://lib.jucs.org/article/27180/download/pdf/
en
10.3217/jucs-001-11-0728
1995-11-28
jucs
Testing a High-Speed Data Path The Design of the RSAb Crypto Chip
Mayerwieser,Wolfgang
Posch,Karl
Posch,Reinhard
Schindler,Volker
high speed multipliers
hardware algorithms
design for testability
public key cryptography
JUCS - Journal of Universal Computer Science 1(11): 728-743
High speed devices for public key cryptography are of emerging interest. For this reason, the crypto chip was designed. It is an architecture capable of performing fast RSA encryption and other cryptographic algorithms based on modulo multiplication. Besides the modulo multiplication algorithm called FastMM, the reasons for its high computation speed are the As Parallel As Possible (APAP) architecture, as well as the high operation frequency. The crypto chip also contains on-chip RAM and a special-purpose control logic, enabling special features like encrypted key loading. However, this control mechanism influences to some extend testability of the MM data path which is the heart of the chip. For this reason, the crypto chip has been designed to be able to evaluate the behaviour of the pure MM data path. In the following, we describe the strategies used with the crypto chip for testing the MM data path under realistical conditions. In this context, analyzing control signal flow turns out to be the key action.This work has been sponsored as part of the project Nr. P9384PHY "Sichere Kommunikation bei hohen Geschwindigkeiten" by the Austrian Science Foundation.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-11-0728
https://doi.org/10.3217/jucs-001-11-0728
https://lib.jucs.org/article/27185/
https://lib.jucs.org/article/27185/download/pdf/
en
10.3217/jucs-001-11-0744
1995-11-28
jucs
A Comparison of WWW and Hyper-G
Pam,Andrew
Vermeer,Arnould
Hypermedia
Hyper-G
WWW
Xanadu
networked information systems
Internet
JUCS - Journal of Universal Computer Science 1(11): 744-750
In this paper we attempt to compare features of WWW and Hyper-G, the first fully operable networked multimedia system that goes much beyond WWW and incorporates many features first proposed in Xanadu and later partially tested in systems such as Intermedia.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-11-0744
https://doi.org/10.3217/jucs-001-11-0744
https://lib.jucs.org/article/27188/
https://lib.jucs.org/article/27188/download/pdf/
en
10.3217/jucs-001-12
1995-12-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 1(12): 751-751
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Editorial
text/html
info:doi:10.3217/jucs-001-12
https://doi.org/10.3217/jucs-001-12
https://lib.jucs.org/article/27190/
https://lib.jucs.org/article/27190/download/pdf/
en
10.3217/jucs-001-12-0752
1995-12-28
jucs
A Novel Type of Skeleton for Polygons
Aichholzer,Oswin
Aurenhammer,Franz
Alberts,David
Gärtner,Bernd
Simple polygon
angular bisectors
internal skeleton
roof construction
JUCS - Journal of Universal Computer Science 1(12): 752-761
A new internal structure for simple polygons, the straight skeleton, is introduced and discussed. It is composed of pieces of angular bisectores which partition the interior of a given n-gon P in a tree-like fashion into n monotone polygons. Its straight-line structure and its lower combinatorial complexity may make the straight skeleton preferable to the widely used medial axis of a polygon. As a seemingly unrelated application, the straight skeleton provides a canonical way of constructing a polygonal roof above a general layout of ground walls.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-12-0752
https://doi.org/10.3217/jucs-001-12-0752
https://lib.jucs.org/article/27191/
https://lib.jucs.org/article/27191/download/pdf/
en
10.3217/jucs-001-12-0762
1995-12-28
jucs
Constraint Agents for the Information Age
Andreoli,Jean-Marc
Borghoff,Uwe
Pareschi,Remo
Schlichter,Johann
multiagent coordination
agent-interaction
distributed problem solving
signed feature constraints
negotiation
cooperation strategies.
JUCS - Journal of Universal Computer Science 1(12): 762-789
We propose constraints as the appropriate computational constructs for the design of agents with the task of selecting, merging and managing electronic information coming from such services as Internet access, digital libraries, E-mail, or on-line information repositories. Specifically, we introduce the framework of Constraint-Based Knowledge Brokers, which are concurrent agents that use so-called signed feature constraints to represent partially specified information and can flexibly cooperate in the management of distributed knowledge. We illustrate our approach by several examples, and we define application scenarios based on related technology such as Telescript and workflow management systems.
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info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-12-0762
https://doi.org/10.3217/jucs-001-12-0762
https://lib.jucs.org/article/27192/
https://lib.jucs.org/article/27192/download/pdf/
en
10.3217/jucs-001-12-0790
1995-12-28
jucs
Parikh Prime Words and GO-like Territories
Mateescu,Alexandru
Paun,Gheorghe
Rozenberg,Grzegorz
Salomaa,Arto
formal languages
context free languages
L-systems
Parikh mapping
word problems
JUCS - Journal of Universal Computer Science 1(12): 790-810
An n-dimensional vector of natural numbers is said to be prime if the greatest common divisor of its components is one. A word is said to be Parikh prime if its Parikh vector is prime. The languages of Parikh prime and of Parikh non-prime words are investigated (they are neither semilinear nor slender, hence are not context-free or D0L languages, both of them can be generated by matrix grammars with appearance checking). Marking in the plane the points identified by prime (2-dimensional) vectors, interesting patterns of non-marked ("free") points appear (they are similar to the territories in the game of GO). The shape of such possible territories is investigated (with an exhaustive analysis of tro-, tetro-, pento- and hexominoes). Some open problems are formulated (both concerning the mentioned languages and the "GO territories theory"). 1.) Research supported by the Academy of Finland, project 11281, and the ESPRIT Basic Research Working Group ASMICS II.
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info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-12-0790
https://doi.org/10.3217/jucs-001-12-0790
https://lib.jucs.org/article/27197/
https://lib.jucs.org/article/27197/download/pdf/
en
10.3217/jucs-001-12-0811
1995-12-28
jucs
Exploiting Parallelism in Constraint Satisfaction for Qualitative Simulation
Platzner,Marco
Rinner,Bernhard
Weiss,Reinhold
Parallel constraint satisfaction
QSim
distributed AI
JUCS - Journal of Universal Computer Science 1(12): 811-820
Constraint satisfaction is very common in many artificial intelligence applications. This paper presents results from parallelizing constraint satisfaction in a special application --- the algorithm for qualitative simulation QSim [Kuipers 94]. A parallel-agent based strategy (PAB) is used to solve the constraint satisfaction problem (CSP). Two essential steps of PAB are studied in more detail to achieve a good performance of the parallel algorithm. Partitioning heuristics to generate independent parts of the overall search space are investigated. Sequential CSP algorithms are compared in order to reveal the most efficient one for QSim. The evaluation of these heuristics and algorithms is based on runtime measurements using CSPs traced from QSim. These runtimes allow a best- and worst-case estimation of the expected speedup of the parallel algorithms. The comparison of sequential CSP algorithms leads to following strategy for solving partitioned problems. Less complex problems are solved with simple backtracking, and more complex models are solved with graph-directed backjumping (GBJ).
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info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-12-0811
https://doi.org/10.3217/jucs-001-12-0811
https://lib.jucs.org/article/27198/
https://lib.jucs.org/article/27198/download/pdf/
en
10.3217/jucs-001-12-0821
1995-12-28
jucs
A Markov Process for Sequential Allocation
Stefanescu,Calina
JUCS - Journal of Universal Computer Science 1(12): 821-827
We describe a Markov process which models the sequential allocation for two adjacent tables coexisting in memory by growing towards each other. The tables are expected to fill at the same rate, random deletions and insertions are allowed. 1.) 1991 Mathematics Subject Classification. Primary 60J20, Secondary 62M05, 68P05.
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J.UCS License
Journal of Universal Computer Science
1995
Research Article
text/html
info:doi:10.3217/jucs-001-12-0821
https://doi.org/10.3217/jucs-001-12-0821
https://lib.jucs.org/article/27200/
https://lib.jucs.org/article/27200/download/pdf/
en
10.3217/jucs-002-01
1996-01-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 2(1): 1-1
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Editorial
text/html
info:doi:10.3217/jucs-002-01
https://doi.org/10.3217/jucs-002-01
https://lib.jucs.org/article/27202/
https://lib.jucs.org/article/27202/download/pdf/
en
10.3217/jucs-002-01-0002
1996-01-28
jucs
Wait-Freedom vs. Bounded Wait Freedom in Public Data Structures
Brit,Hagit
Moran,Shlomo
JUCS - Journal of Universal Computer Science 2(1): 2-19
In this paper we define and study public data structures, which are concurrent data structures in the shared memory environment, which enable access to an unknown (and possibly infinite) set of identical processes. Specific cases of such data structures (like counting networks and concurrent counters) have been studied recently, and such data structures seem to model concurrent systems like client-server applications, in which the identities of the clients, and sometimes also their number, are not known apriori. Specifically, we study the relation between wait-free and bounded wait-free public data structures - the former guarantees that every operation performed on the data structure always terminates, regardless of the relative speed of the processes, the latter guarantees that every such operation is terminated within a fixed number of steps. We present an example of a public data structure which is wait-free but not bounded wait-free, and then we show that if all the concurrent objects of the data structure are periodic, then wait-freedom implies bounded wait-freedom.
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info:eu-repo/semantics/altIdentifier/pissn/0948-695X
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-01-0002
https://doi.org/10.3217/jucs-002-01-0002
https://lib.jucs.org/article/27203/
https://lib.jucs.org/article/27203/download/pdf/
en
10.3217/jucs-002-01-0020
1996-01-28
jucs
LAN Access Over ISDN
Pucher,Franz
Leitold,Herbert
Posch,Reinhard
JUCS - Journal of Universal Computer Science 2(1): 20-33
This paper describes local area network (LAN) access using public wide area data networks and problems that arise when using integrated services digital network (ISDN) technology [Stallings 90] [Thachenkary 93]. To date mainly modem connections at serial lines with a terminal port have been the standard remote access technique. With ISDN it is foreseen that these modem lines will be replaced rather soon. This is mainly due to the fact that ISDN offers a more adequate bandwidth and is much more consistent from the point of view of access and embedding. This paper demonstrates in the main section a router-based solution for enhanced call management. One of the main advantages is the separation of the strategic module which defines the behavior and thus allows for a number of active connections exceeding the number of ports. It also addresses traffic and access control in the network environment.
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-01-0020
https://doi.org/10.3217/jucs-002-01-0020
https://lib.jucs.org/article/27205/
https://lib.jucs.org/article/27205/download/pdf/
en
10.3217/jucs-002-01-0034
1996-01-28
jucs
The Dortmund Family of Hypermedia Models - Concepts and their Application
Tochtermann,Klaus
Dittrich,Gisbert
hypermedia
hypermedia model
hypermedia system
hypermedia structuring
JUCS - Journal of Universal Computer Science 2(1): 34-56
This paper presents the Dortmund Family of Hypermedia Models (DFHM). Existing formal models for hypermedia mostly lack the flexibility and adaptability and, often not more than one existing system conforms to such a model. The DFHM overcomes this drawback by means of optional and alternative data types. The conformance of a hypermedia system to the DFHM can be conditionalised upon one member of the family. The DFHM has been formalised in VDM, but the aim of this paper is to give an informal overview of the main concepts. Therefore, any formalisms are omitted here. The first part of the paper deals with hypermedia fundamentals from a conceptual perspective. Apart from basic concepts, e.g. nodes and links, also structuring concepts, e.g. views, folders and others, are discussed in detail. Some examples are given to convey how models for existing hypermedia systems can be derived from the DFHM. The second part demonstrates the power of these concepts by introducing main features of a hypermedia system that has been developed for the use in educational settings. This hypermedia system bases upon a member of the DFHM.
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info:eu-repo/semantics/altIdentifier/pissn/0948-695X
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-01-0034
https://doi.org/10.3217/jucs-002-01-0034
https://lib.jucs.org/article/27206/
https://lib.jucs.org/article/27206/download/pdf/
en
10.3217/jucs-002-02
1996-02-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 2(2): 57-58
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Editorial
text/html
info:doi:10.3217/jucs-002-02
https://doi.org/10.3217/jucs-002-02
https://lib.jucs.org/article/27209/
https://lib.jucs.org/article/27209/download/pdf/
en
10.3217/jucs-002-02-0058
1996-02-28
jucs
Curve Fitting and Interpolation of Biological Data Under Uncertainties
Markov,Svetoslav
Akyildiz,Y.
Interpolation
least squares approximation
verification
model validation
algebraic manipulations
computer algebra systems
enzyme kinetics
uncertainties
interval arithmetic
JUCS - Journal of Universal Computer Science 2(2): 59-69
This paper is devoted to the software implementation of two mathematical methods which are often used in biological applications: interpolation and curve fitting in the presence of uncertainties in the input data given in the form of intervals. The methods involve model functions linear in their parameters and are formulated by means of simple expressions in terms of interval arithmetic allowing the computation of verified bounds for the interpolating/approximating functions. The methods are demonstrated for certain classes of nonlinear modelling functions finding applications in biology. A case study involving enzyme-catalysed reaction is considered. The numerical results are performed in the computer algebra system Mathematica, which supports interval-arithmetic computations.
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info:eu-repo/semantics/altIdentifier/pissn/0948-695X
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-02-0058
https://doi.org/10.3217/jucs-002-02-0058
https://lib.jucs.org/article/27210/
https://lib.jucs.org/article/27210/download/pdf/
en
10.3217/jucs-002-02-0070
1996-02-28
jucs
Inexact Information Systems and its Application to Approximate Reasoning
Andreeva,Plamena
Linguistic approach
fuzzy implication
fuzzy quantifier
fuzzy number
approximate reasoning
information system.
JUCS - Journal of Universal Computer Science 2(2): 70-76
The inexact information system is based on linguistic terms which have values lying in the interval [0,1]. Imprecision has advantages, because fuzzy sets avoid the rigidity of conventional mathematical reasoning and computer programming. Fuzzy quantifiers are made explicit by means of fuzzy logic. Many systems, for example, complex biological processes, cannot be programmed in a precise way. With fuzzy sets the implicit quantifiers can be easily translated into machine usable form. This paper discusses a method for the description of fuzzy quantifiers in formal languages. A comparison between approximate reasoning and the method of linear interpolation is made. Inexact information in biological and medical expert systems, and the reliability inferences based on it, are also discussed.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-02-0070
https://doi.org/10.3217/jucs-002-02-0070
https://lib.jucs.org/article/27214/
https://lib.jucs.org/article/27214/download/pdf/
en
10.3217/jucs-002-02-0077
1996-02-28
jucs
Dedicated Hardware for Biological Sequence Comparison
Lavenier,Dominique
Hardware
Biological Sequence Comparison
DNA
FPGA
VLSI
JUCS - Journal of Universal Computer Science 2(2): 77-86
Biological sequence comparison is a time consuming task on a Von Neuman computer. The addition of dedicated hardware for parallelizing the comparison algorithms results in a reduction of several orders of magnitude in the execution time. This paper presents and compares different dedicated approaches, based on the parallelization of the algorithms on linear arrays of processors.
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info:eu-repo/semantics/altIdentifier/pissn/0948-695X
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-02-0077
https://doi.org/10.3217/jucs-002-02-0077
https://lib.jucs.org/article/27219/
https://lib.jucs.org/article/27219/download/pdf/
en
10.3217/jucs-002-02-0087
1996-02-28
jucs
On the Scalability of Molecular Computational Solutions to NP Problems
Dónaill,Dónall A. Mac
Molecular Computation
DNA
NP-problem
JUCS - Journal of Universal Computer Science 2(2): 87-95
A molecular computational procedure in which manipulation of DNA strands may be harnessed to solve a classical problem in NP - the directed Hamiltonian path problem - was recently proposed [Adleman 1994], [Gifford 1994]. The procedure is in effect a massively parallel chemical analog computer and has a computational capacity corresponding to approximately CPU years on a typical 10 MFLOP workstation. In this paper limitations on the potential scalability of molecular computation are considered. A simple analysis of the time complexity function shows that the potential of molecular systems to increase the size of generally solvable problems in NP is fundamentally limited to . Over the chemically measurable picomolar to molar concentration range the greatest practical increase in problem size is limited to
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-02-0087
https://doi.org/10.3217/jucs-002-02-0087
https://lib.jucs.org/article/27220/
https://lib.jucs.org/article/27220/download/pdf/
en
10.3217/jucs-002-03
1996-03-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 2(3): 96-96
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Editorial
text/html
info:doi:10.3217/jucs-002-03
https://doi.org/10.3217/jucs-002-03
https://lib.jucs.org/article/27222/
https://lib.jucs.org/article/27222/download/pdf/
en
10.3217/jucs-002-03-0097
1996-03-28
jucs
An Optimal Parallel Algorithm for Learning DFA
Balcázar,José
Díaz,Josep
Gavaldà,Ricard
Watanabe,Osamu
computational learning theory
query learning
membership query
equivalence query
DFA
optimal parallel learning
JUCS - Journal of Universal Computer Science 2(3): 97-112
Sequential algorithms given by Angluin (1987) and Schapire (1992) learn deterministic finite automata (DFA) exactly from Membership and Equivalence queries. These algorithms are feasible, in the sense that they take time polynomial in n and m, where n is the number of states of the automaton and m is the length of the longest counterexample to an Equivalence query. This paper studies whether parallelism can lead to substantially more efficient algorithms for the problem. We show that no CRCW PRAM machine using a number of processors polynomial in n and m can identify DFA in o(n/log n) time. Furthermore, this lower bound is tight up to constant factors: we develop a CRCW PRAM learning algorithm that uses polynomially many processors and exactly learns DFA in time O(n/log n).
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-03-0097
https://doi.org/10.3217/jucs-002-03-0097
https://lib.jucs.org/article/27223/
https://lib.jucs.org/article/27223/download/pdf/
en
10.3217/jucs-002-03-0113
1996-03-28
jucs
Government, Cryptography, and the Right to Privacy
Shearer,Jenny
Gutmann,Peter
JUCS - Journal of Universal Computer Science 2(3): 113-146
The notion of a right to privacy of citizens in their communications is discussed in the context of an international movement by governments towards regulation of cryptography, and consideration of key forfeiture systems in national cryptography use. The authors argue that the right to privacy in communications networks is an issue of major importance, assuring freedom of the individual in national and global communications. Regulation and control of cryptography use on the Internet by national governments may lead to an imbalance in the citizen/government power relationship, with sequelae including unprecedented surveillance of citizens, disruption of international commerce due to lack of powerful cryptography (and lack of standardisation), human rights abuses by less democratic or non-democratic governments, and limiting of the political potential of an Internet global political system.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-03-0113
https://doi.org/10.3217/jucs-002-03-0113
https://lib.jucs.org/article/27225/
https://lib.jucs.org/article/27225/download/pdf/
en
10.3217/jucs-002-03-0147
1996-03-28
jucs
On the Difficulty of Constructing Cryptographically Strong Substitution Boxes
Zhang,Xian-Mo
Zheng,Yuliang
cryptography
differential attack
linear attack
permutations
substitution boxes (S-boxes)
JUCS - Journal of Universal Computer Science 2(3): 147-162
Two significant recent advances in cryptanalysis, namely the differential attack put forward by Biham and Shamir [BS91] and the linear attack by Matsui [Mat94a, Mat94b], have had devastating impact on data encryption algorithms. An eminent problem that researchers are facing is to design S-boxes or substitution boxes so that an encryption algorithm that employs the S-boxes is immune to the attacks. In this paper we present evidence indicating that there are many pitfalls on the road to achieve the goal. In particular, we show that certain types of S-boxes which are seemingly very appealing do not exist. We also show that, contrary to previous perception, techniques such as chopping or repeating permutations do not yield cryptographically strong S-boxes. In addition, we reveal an important combinatorial structure associated with certain quadratic permutations, namely, the difference distribution table of each differentially 2-uniform quadratic permutation embodies a Hadamard matrix. As an application of this result, we show that chopping a differentially 2-uniform quadratic permutation results in an S-box that is very prone to the differential cryptanalytic attack.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-03-0147
https://doi.org/10.3217/jucs-002-03-0147
https://lib.jucs.org/article/27228/
https://lib.jucs.org/article/27228/download/pdf/
en
10.3217/jucs-002-04
1996-04-28
jucs
Managing Editor's Column
Maurer,Hermann
JUCS - Journal of Universal Computer Science 2(4): 163-163
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Editorial
text/html
info:doi:10.3217/jucs-002-04
https://doi.org/10.3217/jucs-002-04
https://lib.jucs.org/article/27230/
https://lib.jucs.org/article/27230/download/pdf/
en
10.3217/jucs-002-04-0164
1996-04-28
jucs
MONSTR I - Fundamental Issues and the Design of MONSTR
Banach,Richard
Intermediate Languages
Term Graph Rewriting
MONSTR
Semantic Models
JUCS - Journal of Universal Computer Science 2(4): 164-216
This is the first in a series of papers dealing with the implementation of an extended term graph rewriting model of computation (described by the DACTL language) on a distributed store architecture. In this paper we set out the high level model, and under some simple restrictions, prove an abstract packet store implementation correct modulo garbage. The abstract packet store model is compared to a more realistic and finegrained packet store model, more closely related to the properties of a genuine distributed store architecture, and the differences are used to inspire the definition of the MONSTR sublanguage of DACTL, intended for direct execution on the machine. Various alternative operational semantics for MONSTR are proposed to reflect more closely the finegrained packet store model, and the prospects for establishing correctness are discussed. The detailed treatment of the alternative models, in the context of suitable sublanguages of MONSTR where appropriate, are subjects for subsequent papers.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-04-0164
https://doi.org/10.3217/jucs-002-04-0164
https://lib.jucs.org/article/27233/
https://lib.jucs.org/article/27233/download/pdf/
en
10.3217/jucs-002-04-0217
1996-04-28
jucs
On Images of Algebraic Series
Honkala,Juha
JUCS - Journal of Universal Computer Science 2(4): 217-223
We show that it is decidable whether or not the set of coefficients of a given Q-algebraic sequence is finite. The same question is undecidable for Q-algebraic series. We consider also prime factors of algebraic series.
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info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-04-0217
https://doi.org/10.3217/jucs-002-04-0217
https://lib.jucs.org/article/27234/
https://lib.jucs.org/article/27234/download/pdf/
en
10.3217/jucs-002-04-0224
1996-04-28
jucs
The Power of Restricted Splicing with Rules from a Regular Language
Kari,Lila
Paun,Gheorghe
Salomaa,Arto
DNA recombination
splicing systems
molecular genetics
Chomsky hierarchy
regulated rewriting
abstract families of languages
JUCS - Journal of Universal Computer Science 2(4): 224-240
We continue the investigations begun in [11] on the relationships between several variants of the splicing operation and usual operations with formal languages. The splicing operations are defined with respect to arbitrarily large sets of splicing rules, codified as simple languages. The closure properties of families in Chomsky hierarchy are examined in this context. Several surprising results are obtained about the generative or computing power of the splicing operation. Many important open problems are mentioned.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
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J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-04-0224
https://doi.org/10.3217/jucs-002-04-0224
https://lib.jucs.org/article/27235/
https://lib.jucs.org/article/27235/download/pdf/
en
10.3217/jucs-002-05
1996-05-28
jucs
Managing Editor's Column
Maurer,Hermann
Calude,Cristian S.
JUCS - Journal of Universal Computer Science 2(5): 241-244
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J.UCS License
Journal of Universal Computer Science
1996
Editorial
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info:doi:10.3217/jucs-002-05
https://doi.org/10.3217/jucs-002-05
https://lib.jucs.org/article/27236/
https://lib.jucs.org/article/27236/download/pdf/
en
10.3217/jucs-002-05-0245
1996-05-28
jucs
Introduction To Algorithmic Information Theory
Markowsky,George
JUCS - Journal of Universal Computer Science 2(5): 245-269
1.) C. Calude (ed.). The Finite, the Unbounded and the Infinite, Proceedings of the Summer School "Chaitin Complexity and Applications", Mangalia, Romania, 27 June - 6 July, 1995.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-05-0245
https://doi.org/10.3217/jucs-002-05-0245
https://lib.jucs.org/article/27237/
https://lib.jucs.org/article/27237/download/pdf/
en
10.3217/jucs-002-05-0270
1996-05-28
jucs
The Limits of Mathematics
Chaitin,G.
JUCS - Journal of Universal Computer Science 2(5): 270-305
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-05-0270
https://doi.org/10.3217/jucs-002-05-0270
https://lib.jucs.org/article/27238/
https://lib.jucs.org/article/27238/download/pdf/
en
10.3217/jucs-002-05-0306
1996-05-28
jucs
Kraft-Chaitin Inequality Revisited
Calude,Cristian S.
Grozea,Cristian
Kraft inequality
Kraft-Chaitin inequality
prefix-free codes
JUCS - Journal of Universal Computer Science 2(5): 306-310
Kraft's inequality [9] is essential for the classical theory of noiseless coding [1, 8]. In algorithmic information theory [5, 7, 2] one needs an extension of Kraft's condition from finite sets to (infinite) recursively enumerable sets. This extension, known as Kraft-Chaitin Theorem, was obtained by Chaitin in his seminal paper [4] (see also, [3, 2]). The aim of this note is to offer a simpler proof of Kraft-Chaitin Theorem based on a new construction of the prefix-free code. 1.) C. Calude (ed.). The Finite, the Unbounded and the Infinite, Proceedings of the Summer School "Chaitin Complexity and Applications", Mangalia, Romania, 27 June - 6 July, 1995. 2.) The work of the first author has been partially supported by Auckland University Research Grant A18/ XXXXX/62090/3414050.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-05-0306
https://doi.org/10.3217/jucs-002-05-0306
https://lib.jucs.org/article/27239/
https://lib.jucs.org/article/27239/download/pdf/
en
10.3217/jucs-002-05-0311
1996-05-28
jucs
Quantum Algorithmic Information Theory
Svozil,Karl
JUCS - Journal of Universal Computer Science 2(5): 311-346
The agenda of quantum algorithmic information theory, ordered `top-down, is the quantum halting amplitude, followed by the quantum algorithmic information content, which in turn requires the theory of quantum computation. The fundamental atoms processed by quantum computation are the quantum bits which are dealt with in quantum information theory. The theory of quantum computation will be based upon a model of universal quantum computer whose elementary unit is a two-port interferometer capable of arbitrary U(2) transformations. Basic to all these considerations is quantum theory, which is most conveniently expressible in Hilbert space. 1.) C. Calude (ed.). The Finite, the Unbounded and the Infinite, Proceedings of the Summer School "Chaitin Complexity and Applications", Mangalia, Romania, 27 June - 6 July, 1995.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-05-0311
https://doi.org/10.3217/jucs-002-05-0311
https://lib.jucs.org/article/27240/
https://lib.jucs.org/article/27240/download/pdf/
en
10.3217/jucs-002-05-0347
1996-05-28
jucs
Towards Foundations of Cryptography: Investigation of Perfect Secrecy
Jürgensen,H.
Robbins,L.
cryptography
perfect secrecy
program-size complexity
information theory
computational complexity
JUCS - Journal of Universal Computer Science 2(5): 347-379
In the spirit of Shannon s theory of secrecy systems we analyse several possible natural definitons of the notion of perfect secrecy, these definitions are based on arguments taken from probability theory, information theory, the theory of computational complexity, and the theory of program-size complexity or algorithmic information. It turns out that none of these definitions models the intuitive notion of perfect secrecy completely: Some fail because a cryptographic system with weak keys can be proven to achieve perfect secrecy in their framework, others fail, because a system which, intuitively, achieves perfect secrecy cannot be proven to do so in their framework. To present this analysis we develop a general formal framework in which to express and measure secrecy aspects of information transmission systems. Our analysis leads to a clarification of the intuition which any definition of the notion of perfect secrecy should capture and the conjecture, that such a definition may be impossible, that is, that only secrecy by degrees can be defined rigorously. This analysis also leads to a clarification of what the cryptographic literature refers to as the one-time pad. On the basis of the arguments used for its strength in the literature, one has to distinguish between two quite different systems: the first kind uses randomly chosen strings of some given length, the second kind uses random strings, that is, patternless strings of some given length. The former achieves perfect secrecy in the sense of Shannon, but permits weak keys - like the all-zero key, the latter, while intuitively stronger, does not achieve perfect secrecy in any of the proposed senses. Finally, the analysis exposes the need for a formal, non-operational, but mathematical definition of the notion of weak key. 1.) C. Calude (ed.). The Finite, the Unbounded and the Infinite, Proceedings of the Summer School "Chaitin Complexity and Applications", Mangalia, Romania, 27 June - 6 July, 1995. The research reported in this paper was supported by the Natural Sciences and Engineering Council of Canada, Grant OGP0000243.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-05-0347
https://doi.org/10.3217/jucs-002-05-0347
https://lib.jucs.org/article/27242/
https://lib.jucs.org/article/27242/download/pdf/
en
10.3217/jucs-002-05-0380
1996-05-28
jucs
Is Finite Precision Arithmetic Useful For Physics ?
Chaitin-Chatelin,Françoise
JUCS - Journal of Universal Computer Science 2(5): 380-395
Both empirical sciences and computations are fundamentally restricted to measurements/computations involving a finite amount of information. These activities deal with the FINITE - some finite precision numbers, coming out from measurements, or from calculations run for some finite amount of time. By way of contrast, as Leibniz expressed it, mathematics is the science of the INFINITE, which contains the concept of continuum. The related concepts of limit points, derivatives and Cantor sets also belong to mathematics, the realm of the infinite, and not to the world of the finite. One is then lead to wonder about the basis for the "unreasonable effectiveness of mathematics in the natural sciences" (Wigner (1960). This puzzling situation gave birth, over the centuries, to a very lively philosophical discussion between mathematicians and physicists. We intend to throw into the debate a few simple examples drawn from practice in numerical analysis as well as in finite precision computations. By means of these examples, we illustrate some aspects of the subtle interplay between the discrete and the continuous, which takes place in Scientific Computing, when solving some equations of Physics.Is Nature better described by discrete or continuous models at its most intimate level, that is below the atomic level? With the theory of quantum physics, it seems that the question has received a significant push towards a discrete space. However one can argue equally that the time variable in Schrödinger's equation is continuous. We will not get involved in the scholarly dispute between the continuous and the discrete. Instead, we will show on simple examples taken from Scientific Computing, the subtlety of the interplay between the continuous and the discrete, which can take place in computations, be it with finite precision or exact arithmetic. 1.) C. Calude (ed.). The Finite, the Unbounded and the Infinite, Proceedings of the Summer School "Chaitin Complexity and Applications", Mangalia, Romania, 27 June - 6 July, 1995.
info:eu-repo/semantics/altIdentifier/eissn/0948-6968
info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-05-0380
https://doi.org/10.3217/jucs-002-05-0380
https://lib.jucs.org/article/27245/
https://lib.jucs.org/article/27245/download/pdf/
en
10.3217/jucs-002-05-0396
1996-05-28
jucs
Polynomials, Constructivity and Randomness
Ştefănescu,Doru
JUCS - Journal of Universal Computer Science 2(5): 396-409
We discuss some effective characterizations of the prime elements in a polynomial ring and polynomial factorization techniques. We emphasize that some factorization methods are probabilistic, their efficiency justifies the experimental trend in mathematics. The possibility of an effective version of Hilbert's irreducibility theorem and the probabilistic techniques of Berlekamp will be also discussed. Finally, bounds on the heights of integer polynomials are used as tools for improving polynomial factorizations. 1 C. Calude (ed.). The Finite, the Unbounded and the Infinite, Proceedings of the Summer School "Chaitin Complexity and Applications", Mangalia, Romania, 27 June - 6 July, 1995.
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info:eu-repo/semantics/altIdentifier/pissn/0948-695X
info:eu-repo/semantics/openAccess
J.UCS License
Journal of Universal Computer Science
1996
Research Article
text/html
info:doi:10.3217/jucs-002-05-0396
https://doi.org/10.3217/jucs-002-05-0396
https://lib.jucs.org/article/27247/
https://lib.jucs.org/article/27247/download/pdf/
en
cGFnZT0xJnNldD1qdWNzJmZyb209JnVudGlsPSZtZXRhZGF0YV9wcmVmaXg9b2FpX2Rj