DOI: 10.3897/jucs.154672

Authors: Aleksandar Velinov, Aleksandra Mileva, Simon Volpert, Sebastian Zillien, Steffen Wendzel

Abstract: Network steganography has existed for several decades and it uses network traffic and network protocols as carriers for embedding secret messages in a stealthy manner. Quick UDP Internet Connections (QUIC) is a novel secure and reliable transport layer network protocol that is encapsulated in the User Datagram Protocol (UDP) and utilizes the Transport Layer Security Version 1.3 (TLSv1.3) standard. In addition, Hypertext Transfer Protocol Version 3 (HTTP/3) employs QUIC. In this paper, we present a systematic analysis of the covert channels that can be found in QUIC. Twenty novel covert channels are identified by applying the latest covert channel pattern based taxonomy, and an analysis of their transmission rate, undetectability, and robustness is presented, together with suggested countermeasures. A single covert channel is implemented as a proof of concept tool and is appropriately evaluated.

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DOI: 10.3897/jucs.2020.078

Authors: Dawid Ewald, Hubert Zarzycki, Łukasz Apiecionek, Jacek Czerniak

Abstract: The paper presents an innovative OFNBee optimization method based on combining the swarm intelligence with the use of directed fuzzy numers OFN. In the introduction, the issues related to the subject of the study, including bee algorithms and OFN numbers, were reviewed. The innovative OFNBee algorithm was presented and verified against a set of known benchmarks functions such as Sphere, Rastrigin, Griewank, Rosenbrock, Schwefel and Ackley. These functions have been applied due to their reliability in the literature. In the further part of the study, the configuration of the algorithm parameters is carried out, including the launch of each mathematical function several dozen times for different data, such as different population sizes. The key part of the research and analysis was to compare OFNBee with six standard ABC, MBO, IMBO, TLBO, HBMO, BBMO bee algorithms. The article ends with a summary and an indication of the possible future works.

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DOI: 10.3897/jucs.2020.070

Authors: Jisha Maniamma, Hiroaki Wagatsuma

Abstract: Bongard Problems (BPs) are a set of 100 visual puzzles introduced by M. M. Bongard in the mid-1960s. BPs have been established as benchmark puzzles for understanding the human context-based learning abilities to solve ill- posed problems. The puzzle requires the logical explanation as the answer to distinct two classes of figures from redundant options, which can be obtained by a thinking process to alternatively change the target frame (hierarchical level of analogy) of thinking from a wide range concept networks as D. R. Hofstadter suggested. Some minor research results to solve a limited set of BPs have reported based a single architecture accompanied with probabilistic approaches; however the central problem on BP's difficulties is the requirement of flexible changes of the target frame, therefore non-hierarchical cluster analyses does not provide the essential solution and hierarchical probabilistic models needs to include unnecessary levels for learning from the beginning to prevent a prompt decision making. We hypothesized that logical reasoning process with limited numbers of meta-data descriptions realizes the sophisticated and prompt decision-making and the performance is validated by using BPs. In this study, a semantic web-based hierarchical model to solve BPs was proposed as the minimum and transparent system to mimic human-logical inference process in solving of BPs by using the Description Logic (DL) with assertions on concepts (TBox) and individuals (ABox). Our results demonstrated that the proposed model not only provided individual solutions as a BP solver, but also proved the correctness of Hofstadter's idea as the flexible frame with concept networks for BPs in our actual implementation, which no one has ever achieved. This fact will open the new horizon for theories for designing of logical reasoning systems especially for critical judgments and serious decision-making as expert humans do in a transparent and descriptive way of why they judged in that manner.

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DOI: 10.3897/jucs.2020.039

Authors: Mariusz Topolski

Abstract: The vast majority of medical problems are characterised by the relatively high spatial dimensionality of the task, which becomes problematic for many classic pattern recognition algorithms due to the well-known phenomenon of the curse of dimensionality. This creates the need to develop methods of space reduction, divided into strategies for the selection and extraction of features. The most commonly used tool of the second group is the PCA, which, unlike selection methods, does not select a subset of the original set of features and performs its mathematical transformation into a less dimensional form. However, natural downside of this algorithm is the fact that class context is not present in supervised learning tasks. This work proposes a feature extraction algorithm using the approach of the pca method, trying not only to reduce the feature space, but also trying to separate the class distributions in the available learning set. The problematic issue of the work was the creation of a method of feature extraction describing the prognosis for a chronic lymphocytic leukemia type B-CLL, which will be at least as good, or even better than when compared to other quality extractions. The purpose of the research was accomplished for binary and three-class cases in the event in which for verification of extraction quality, five algorithms of machine learning were applied. The obtained results were compared with the application of paired samples Wilcoxon test.

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DOI: 10.3217/jucs-025-09-1174

Authors: Ziad Al-Sharif, Mohammed Al-Saleh, Yaser Jararweh, Ahmed Shatnawi

Abstract: Identifying the software used in a cybercrime can play a key role in establishing the evidence against the perpetrator in the court of law. This can be achieved by various means, one of which is to utilize the RAM contents. RAM comprises vital information about the current state of a system, including its running processes. Accordingly, the memory footprint of a process can be used as evidence about its United States of Americage. However, this evidence can be influenced by several factors. This paper evaluates three of these factors. First, it evaluates how the used programming language affects the evidence. Second, it evaluates how the used platform affects the evidence. Finally, it evaluates how the search for this evidence is influenced by the implicitly used encoding scheme. Our results should assist the investigator in its quest to identify the best amount of evidences about the used software based on its execution logic, host platform, language used, and the encoding of its string values. Results show that the amount of digital evidence is highly affected by these factors. For instance, the memory footprint of a Java based software is often more traceable than the footprints of languages such as C++ and C#. Moreover, the memory footprint of a C# program is more visible on Linux than it is on Windows or Mac OS. Hence, often software related values are successfully identified in RAM memory dumps even after the program is stopped.

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DOI: 10.3217/jucs-024-07-0935

Authors: Alaa Qaffas, Alexandra Cristea, Mohamed Mead

Abstract: Adaptive online advertising is a rapidly expanding marketing tool that delivers personalised messages and adverts to Internet users. At a time when the Internet is burgeoning, many websites use an adaptation process to tailor their advertisements, however, often in an ad-hoc manner. Thus, a new model that guarantees a systematic integration of adaptive features on existing business websites has become an urgent requirement to satisfy customers. This paper aims to solve this issue, by presenting an innovative model for e-advertising adaptation: the Layered Adaptive Advertising Integration (LAAI). LAAI is building upon previous models and frameworks from different domains, by selecting and adding novel features appropriate for e-advertising. Based on this model, a new adaptation system -AEADS - is developed, to test and evaluate the LAAI model. This research also reports on the perception on the methods towards obtaining generalisation, portability and efficiency, as proposed by the LAAI model, by evaluating how a range of businesses are enabled to adapt their advertisements based on user profiles and behaviours.

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DOI: 10.3217/jucs-023-09-0907

Authors: Mohsen Shahriari, Sabrina Haefele, Ralf Klamma

Abstract: Nowadays, people use online social networks almost every day. They activate either due to their interests, or to search or catch their desirable information. Users of online social networks generate structural and contextual traces that can be analyzed by, i.e., network science researchers. Researchers can describe networks fabricated out of online traces from different perspectives that one of them is communities. Overlapping communities are overlapped structures, in which nodes have denser connections with each other than the rest of the network. Different approaches have addressed this problem; however, few analyses and methods have focused on contextual traces generated by users. As such, in this paper, we propose an algorithm that uses actual content produced by users. This algorithm uses term frequency of words generated by users and combines them by an extended clustering technique. Our evaluation results compare the proposed content-based community detection with structural-based methods. We also reveal community properties as well as its relation to contextual information. Administrators can use these algorithms in question & answer forums where the explicit links among users are missing.

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DOI: 10.3217/jucs-021-03-0473

Authors: Hongyu Liu, Leiting Chen, Zahra Davar, Mohammad Pour

Abstract: Cloud storage has a long string of merits but at the same time, poses many challenges on data integrity and privacy. A cloud data auditing protocol, which enables a cloud server to prove the integrity of stored files to a verifier, is a powerful tool for secure cloud storage. Wang et al. proposed a privacy-preserving public auditing protocol, however, Worku et al. found the protocol is seriously insecure and proposed an improvement to remedy the weakness. In this paper, unfortunately, we demonstrate that the new protocol due to Worku et al. fails to achieve soundness and obtains merely limited privacy. Specifically, we show even deleting all the files of a data owner, a malicious cloud server is able to generate a response to a challenge without being caught by TPA in their enhanced but unrealistic security model. Worse still, the protocol is insecure even in a correct security model. For privacy, a dishonest verifier can tell which file is stored on the cloud. Solutions to efficient public auditing mechanisms with perfect privacy protection are still worth exploring.

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DOI: 10.3217/jucs-021-03-0454

Authors: Zhusong Liu, Hongyang Yan, Zhiqiang Lin, Lingling Xu

Abstract: Cloud computing is an emerging computing paradigm that can provide storage resources and computing capacities services over the Internet. However, some new security issues arise when users' sensitive data are outsourced and shared in untrusted cloud. The traditional techniques to protect the confidentiality of sensitive data stored in cloud are encryption and related cryptographic tools. And the corresponding private keys to access and decrypt the files are disclosed to only authorized users. However, these traditional solutions are not scalable because the computational cost of encryption and other access control is heavy for devices with limited computation ability. In this paper, we present a new way to implement scalable and fine-grained access control systems, which can be applied for big data in untrusted cloud computing environment. The solution is based on symmetric, efficient broadcast encryption and fine-grained attribute-based encryption (ABE). In this access control system, users are able to join and revoked with broadcast encryption. An outsourced Hierarchical ABE scheme is first proposed in this paper to construct the access control system. The security analysis is also

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DOI: 10.3217/jucs-021-03-0406

Authors: Chien-Ming Chen, Tsu-Yang Wu, Raylin Tso, Masahiro Mambo, Mu-En Wu

Abstract: Mobile data traffic has been growing at an increasing rate with the popularity of smartphones, tablets, and other wireless devices. To reduce the load on the network, mobile network operators deploy femtocells to increase their coverage and performance and to eliminate wireless notspots. Femtocells are low-cost devices that connect a new femtocell network architecture to the core telecommunication network through a licensed spectrum and standardized interface protocols. In this paper, we first note that the user equipment registration procedure, which is defined in the 3GPP (Third Generation Partnership Project) standard, in a femtocellenabled network is vulnerable to denial-of-service attacks. We then propose a mechanism to defend against these attacks. For compatibility, the proposed mechanism makes use of the well-defined control message in the 3GPP standard and modifies the user equipment registration procedure as little as possible.

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DOI: 10.3217/jucs-019-15-2320

Authors: Karol Rástočný, Michal Tvarožek, Maria Bielikova

Abstract: Information seeking on the Web has become day-to-day routine for more than two billion human beings most of who use traditional keyword-based search engines. Developers of these search engines stress personalization, prediction of users' next actions and mistake correction. But they are still struggling with results presentation and support for users, who make atypical queries or who do not exactly know what they are looking for. We address these issues via a novel approach for exploring web repositories, which naturally combines user search activities - look up, learning and investigation. We achieve this via view-based navigation in hierarchical clusters and two-dimensional graphs of search results.

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DOI: 10.3217/jucs-019-12-1718

Authors: Khalil ur Rehman Laghari, Tiago Falk, Mansoor Hyder, Michael Haun, Christian Hoene, Noel Crespi

Abstract: Quality of Experience (QoE) is a human centric quality evaluation method which provides the blue print of human needs, perceptions, feelings and experiences with respect to a multimedia service. In a communications ecosystem, human interaction takes place alongside technological, contextual, and business domains, thus producing a holistic view on QoE formation. In this paper, we investigate the relationship between human perceived QoE and "context" for burgeoning 3-dimensional (3D) audio teleconferencing services. 3D audio teleconferencing applications are customizable by generating different virtual acoustic environments (VAE), where parameters such as virtual room size and competing talker conditions can be adjusted for a particular application. The impact of different VAE characteristics on perceived QoE, however, is still unknown. In this study, four QoE factors were investigated across different VAE scenarios. It was found that a) medium-size virtual rooms produce optimal perceived QoE, b) competing talkers of mixed gender could be easily located in the virtual space, and c) competing speaker gender had no significant effect on perceived audio quality.

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DOI: 10.3217/jucs-019-10-1351

Authors: Jia Fan, Yuliang Zheng, Xiaohu Tang

Abstract: Signcryption is a public key cryptographic technique that is particularly suited for mobile communications thanks to its light computational and communication overhead. The wide spread use of signcryption in a mobile computing environment, however, is accompanied by an increased risk of private key exposure. This paper addresses the issue of key exposure by proposing a key-insulated signcryption technique. We define a security model for key-insulated signcryption and prove that the keyinsulated signcryption technique is provably secure in the security model.

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DOI: 10.3217/jucs-019-08-1025

Authors: Jose Luis González Sánchez, Roberto García, Josep Brunetti, Rosa Gil, Juan Gimeno

Abstract: In order to make Semantic Web tools more appealing to lay-users, a key factor is their Quality in Use, the quality of the user experience when interacting with them. To assess and motivate the improvement of the quality in use, it is necessary to have a quality model that guides its evaluation and facilitates comparability. The proposal is based on the international standard ISO/IEC 25010:2011 and focuses on Semantic Web exploration tools, those that make it possible for lay-users to browse and visualise it. The model is applied to compare the three main Semantic Web exploration tools that feature facets and the pivoting operation. The analysis assesses that the work being carried out with one of them, as part of a User-Centred Development process with iterative user evaluations, outperforms the other two tools.

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DOI: 10.3217/jucs-018-19-2686

Authors: Gislaine Camila Lapasini Leal, Ana Chaves, Elisa Hatsue Moriya Huzita, Marcio Delamaro

Abstract: The Distributed Software Development (DSD) is a development strategy that meets the globalization needs concerned with the increase productivity and cost reduction. However, the temporal distance, geographical dispersion and the socio-cultural di_erences, increased some challenges and, especially, added new requirements related with the communication, coordination and control of projects. Among these new demands there is the necessity of a software process that provides adequate support to the distributed software development. This paper presents an integrated approach of software development and test that considers distributed teams peculiarities. The approach purpose is to o_er support to DSD, providing a better project visibility, improving the communication between the development and test teams, minimizing the ambiguity and di_culty to understand the artifacts and activities. This integrated approach was conceived based on four pillars: (i) to identify the DSD peculiarities concerned with development and test processes, (ii) to de_ne the necessary elements to compose the integrated approach of development and test to support the distributed teams, (iii) to describe and specify the workows, artifacts, and roles of the approach, and (iv) to represent appropriately the approach to enable the e_ective communication and understanding of it.

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DOI: 10.3217/jucs-018-18-2516

Authors: David Griol, José Molina, Araceli De Miguel, Zoraida Callejas

Abstract: Social Networking has been a global consumer phenomenon during the last few years. Online communities are changing the way people behave, share and interact within their daily lives. Most of such communities are mainly focused on sharing contents and communicating using a traditional web interface. However, social virtual worlds are computer-simulated environments that the users can "inhabit" and in which they can interact and create objects. Education is one of the most interesting applications of virtual worlds, as their flexibility can be exploited in order to create heterogeneous groups from all over the world who can collaborate synchronously in different virtual spaces. In this paper, we highlight the potential of virtual worlds as an educative tool and propose a model to create learning environments within Second Life or OpenSimulator combining the Moodle learning management system, embodied conversational metabots, and programmable 3D objects. We have implemented the proposal in a learning system for several subjects of the Computer Science degree in our university and show that it fostered engagement and collaboration and helped the students to better understand complex concepts.

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DOI: 10.3217/jucs-018-17-2474

Authors: Valeria De Castro, Juan Vara, Esperanza Marcos

Abstract: During the last years, Web Information Systems have evolved from simple information sources to systems offering services to end-users. The development of this kind of systems presents different challenges, such as the alignment between business services and their implementation, and the way business processes are placed in the system. To address this type of challenges this paper presents a methodological and technical proposal for Service-Oriented development of Web Information Systems. It follows a model-driven approach, defining a set of models at different levels of abstraction and the model transformations needed to connect them. Besides, the development of a conference management system is used as case study to illustrate the proposal.

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DOI: 10.3217/jucs-018-12-1662

Authors: Thijs Baars, Marco Spruit

Abstract: When IS/IT needs to be replaced, cloud systems might provide a feasible solution. However, the adoption process thus far has gone undocumented and enterprise architects are troubled with proper hands-on tools missing, until very recently. This single case study describes a large Dutch utility provider in their effort to understand the facets of the cloud and identifying the risks associated with it. In an action research setting, the SeCA model was used to analyse the cloud solutions and identify the risks with specific data classifications in mind. The results show how decision makers can use the SeCA model in various ways to identify the security risks associated with each cloud solution analysed. The analysis assumes that data classifications are in place. This research concludes that by using the SeCA model, a full understanding of the security risks can be gained on an objective and structural level; this is a further validation of prior empirical research that the SeCA model is a proper hands-on tool for cloud security analysis.

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DOI: 10.3217/jucs-018-11-1410

Authors: Jordán Espada, Oscar Martínez, B. Cristina Pelayo G-Bustelo, Juan Manuel Cueva Lovelle, Patricia Ordóñez de Pablos

Abstract: Nowadays mobile devices are equipped with sensors and hardware elements capable of capturing many types of information from the real world, location, orientation, light level, temperature, etc. This information is known in some areas as context information. For years many mobile native applications use context information to support specific tasks. Most of the applications developed with traditional technologies don’t have mechanisms to use most types of context information. This paper presents a lightweight approach to use context information in conventional web applications. The proposal defines a set of highly customizable XML tags, and included web applications that can express specific requests for context information. A web browser designed following the proposed specification is responsible for processing the XML tags and send the context information to the web application using web services. In this paper we present the proposed architecture, then develop and evaluate a GPS navigator application based on this proposal.

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DOI: 10.3217/jucs-018-04-0532

Authors: Joo Lee, Yue Duan, Jae Oh, Wenliang Du, Howard Blair, Lusha Wang, Xing Jin

Abstract: We develop two social network based algorithms that automatically compute author reputation from a collection of textual documents. We first extract keyword reference behaviors of the authors to construct a social network, which represents relationships among the authors in terms of information reference behavior. With this network, we apply the two algorithms: the first computes each author's reputation value considering only direct reference and the second utilizes indirect reference recursively. We compare the reputation values computed by the two algorithms and reputation ratings given by a human domain expert. We further evaluate the algorithms in email categorization tasks by comparing them with machine learning techniques. Finally, we analyse the social network through a community detection algorithm and other analysis techniques. We observed several interesting phenomena including the network being scale-free and having a negative assortativity.

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DOI: 10.3217/jucs-018-03-0314

Authors: Stefan Minder, Michele Notari, Felix Schmitz, Rainer Hofer, Ulrich Woermann

Abstract: The Medical Faculty of the University of Bern uses voice-over in picture driven e-learning modules to avoid split attention induced by the modality effect. To lower production costs, professional narrators have been replaced by computer-generated voices. The e-learning modules are produced with a content management system (CMS) offering text-to-speech functionality. 107 Swiss high school students passed a 20-minute e-learning sequence on cystic fibrosis. In a nested between-group design with four learning content presentation modalities (written text vs. human voice-over vs. artificial voice-over plus 15"-laptop-screens vs. 2,8"smart-phone screens), the learning outcome was assessed at three points in time: before, just after, and six weeks after the learning phase. All modalities led to significant short-term and long-term increase in factual knowledge about cystic fibrosis. Our two hypotheses are supported: (1) presenting pictures with both human and artificial voice-over leads to the same factual learning outcome, and (2) the e-learning module leads to the same learning outcome and acceptance independent of devices and their screen sizes. Furthermore, the image-voice-over modality on mobile devices (small screens) turned out to be a setting with no significant difference in effectiveness.

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DOI: 10.3217/jucs-018-01-0062

Authors: Jesus Boticario, Alejandro Rodriguez-Ascaso, Olga Santos, Emmanuelle Raffenne, Lydia Montandon, David Roldán, Félix Buendía

Abstract: The EU4ALL project (IST-FP6-034778) has developed a general framework to address the needs of accessible lifelong learning at Higher Education level consisting of several standards-based interoperable components integrated into an open web service architecture aimed at supporting adapted interaction to guarantee students' accessibility needs. Its flexibility has supported the project implementation at several sites with different settings and various learning management systems. Large-scale evaluations involving hundreds of users, considering diverse disability types, and key staff roles have allowed obtaining valuable lessons with respect to "how to adopt or enhance eLearning accessibility" at university. The project was evaluated at four higher education institutions, two of the largest in Europe and two medium-sized. In this paper, we focus on describing the implementation and main conclusions at the largest project evaluation site (UNED), which was involved in the project from the beginning, and thus, in the design process, and a medium-sized university that adopted the EU4ALL approach (UPV). This implies dealing with two well-known open source learning environments (i.e. dotLRN and Sakai), and considering a wide variety of stakeholders and requirements. Thus the results of this evaluation serve to illustrate the coverage of both the approach and developments.

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DOI: 10.3217/jucs-017-13-1830

Authors: Michal Holub, Mária Bieliková

Abstract: Nowadays we see successive transformation of the Web into its personalized form. In order to personalize the content to suit e ach user's requirements we need to acquire the user's interests. Utilization of implicit feedback is the most suitable and unobtrusive way of doing so. In this paper we present various forms of implicit feedback and their application in the estimation of user's interests. We propose a method of link recommendation based on the recorded actions users take while visiting a website. We employ collaborative filtering to predict user interest to unvisited pages. We present an evaluation of our method using the web portal of our faculty where personalized recommendation of links to interesting events is provided for visitors.

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DOI: 10.3217/jucs-017-07-1043

Authors: Carlos Solis, Nour Ali

Abstract: Spatial Hypertext Wiki (ShyWiki) is a wiki which represents knowledge using notes that are spatially distributed in wiki pages and have visual characteristics such as colour, size, or font type. The use of spatial and visual characteristics in wikis is important to improve human comprehension, creation and organization of knowledge. Another important capability in wikis is to allow machines to process knowledge. Wikis that formally structure knowledge for this purpose are called semantic wikis. This paper describes how ShyWiki can make use of spatial hypertext in order to be a semantic wiki. ShyWiki can represent knowledge at different levels of formality. Users of ShyWiki can annotate the content and represent semantic relations without being experts of semantic web data description languages. The spatial hypertext features make it suitable for users to represent unstructured knowledge and implicit graphic relations among concepts. In addition, semantic web and spatial hypertext features are combined to represent structured knowledge. The semantic web features of ShyWiki improve navigation and publish the wiki knowledge as RDF resources, including the implicit relations that are analyzed using a spatial parser.

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DOI: 10.3217/jucs-017-04-0605

Authors: Peter Schultes, Franz Lehrer, Harald Kosch

Abstract: Interactive video is increasingly becoming a more and more dominant feature of our media platforms. Especially due to the popular YouTube annotations framework, integrating graphical annotations in a video has become very fashionable these days. However, the current options are limited to a few graphical shapes for which the user can define as good as no dynamic behaviour. Despite the enormous demand for easy-creatable, interactive video there are no such advanced tools available. In this article we describe an innovative approach, to realize dynamics and interactivity of video annotations. First we explain basic concepts of video-markup like the generic element model and visual descriptors. After that we introduce the event-tree model, which can be used to define event-handling in an interactive video formally as well as visually. By combining these basic concepts, we can give an effective tool to the video community for realizing interactive and dynamic video in a simple, intuitive and focused way.

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DOI: 10.3217/jucs-017-01-0064

Authors: Renato Bulcão-Neto, José Camacho-Guerrero, Marcio Dutra, Álvaro Barreiro, Javier Parapar, Alessandra Macedo

Abstract: Due to both the widespread and multipurpose use of document images and the current availability of a high number of document images repositories, robust information retrieval mechanisms and systems have been increasingly demanded. This paper presents an approach to support the automatic generation of relationships among document images by exploiting Latent Semantic Indexing (LSI) and Optical Character Recognition (OCR). We developed the LinkDI (Linking of Document Images) service, which extracts and indexes document images content, computes its latent semantics, and defines relationships among images as hyperlinks. LinkDI was experimented with document images repositories, and its performance was evaluated by comparing the quality of the relationships created among textual documents as well as among their respective document images. Considering those same document images, we ran further experiments in order to compare the performance of LinkDI when it exploits or not the LSI technique. Experimental results showed that LSI can mitigate the effects of usual OCR misrecognition, which reinforces the feasibility of LinkDI relating OCR output with high degradation.

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DOI: 10.3217/jucs-016-15-2038

Authors: Marino Linaje, Juan Preciado, Fernando Sánchez-Figueroa

Abstract: Model-Driven Development concepts are exhibiting as a good engineering solution for the design of ubiquitous applications with multi-device user interfaces and other context-aware capacities. The Web has become an ideal platform for the deployment of such applications and therefore traditional Web development techniques are rapidly adopting Model-Driven principles to cope with the adaptation issues imposed by context-awareness and multichannel solutions. This discipline is being known as Model Driven Web Engineering. However, at the same time that the use of the Web and the number of people with mobile devices is growing, users are demanding more and better user experiences through the user interface. Web vendors answered introducing Rich Internet Applications that take advantage of the single-page paradigm and expand traditional Web features, providing richer content types, richer controls, richer temporal behaviors, richer interactivity and richer communications. While many recent devices support some type of RIA technology, RIAs extended features are showing some limitations of Model Driven Web Engineering methodologies to cope with multi-device context-awareness at the presentation level. This paper presents the combination of two different methodologies, WebML and RUX-Method, both using MDD principles, to obtain multi-device context-aware Rich Internet Applications using a Model-Driven approach. While WebML provides context-awareness at the data and business logic levels, RUX-Method deals with the presentation issues introduced by Rich Internet Applications.

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DOI: 10.3217/jucs-015-13-2463

Authors: Dong-Wook Seo, Hyun-Uk Chae, Byeong-Woo Kim, Won-Ho Choi, Kang-Hyun Jo

Abstract: We propose a method for detection and tracking for objects under multiple cameras system. To track objects, one need to establish correspondence objects among multiple views. We apply the principal axis of objects and the homography constraint to match objects across multiple cameras. The principal axis belongs to the silhouette of objects that is extracted by the background subtraction. We use the multiple background model to the background subtraction. In an image sequence, many changes happen with respect to pixel intensity. This cannot be characterized by the single background model so that is necessary to use the multiple background model. Also, we use the median background model reducing some noises. The silhouette is detected by difference with background models and current image which includes moving objects. For calculating homography, we use landmarks on the ground plane in 3D space. The homography means the relation between two correspondence between two coinciding points from different views. The intersection of principal axes and ground plane in 3D space are the same point shown in each view. The intersection occurs when a principal axis in an image crosses to the transformed ground plane from another image. We construct the correspondence which means the relationship between intersection in current image and transformed intersection from the other image by homography constraint. Those correspondences confirm within a short distance measuring in the top viewed plane. Thus, we track a person by these corresponding points on the ground plane.

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DOI: 10.3217/jucs-015-10-2078

Authors: Elhadi Shakshuki, Richard Halliday

Abstract: Studying and understanding algorithms is important for all computer scientists. Over two decades of research has been devoted to improving algorithm visualization and algorithm explanation techniques. Knowledge gained from these practices allows us to design and implement logically correct programs with considerations to runtime and memory constraints. For many students, learning algorithms in a traditional manner (i.e. using text-books) is challenging. We have developed an alternative approach to teaching algorithms called the Structured Hypermedia Algorithm Explanation (SHALEX) system, which uses hypermedia and represents algorithms as an abstract tree structure. Although SHALEX is a fully functioning teaching tool, currently it does not provide a way of receiving feedback on student’s progress. To address this problem, this paper extends SHALEX with intelligent agent to monitor student progress, to provide the student with hints where necessary and to record the results of student interaction, all of which provide a means of quantifying the level of understanding the student has achieved. The system is implemented as a web-based application using the client-server architecture. This allows students to learn algorithms through both distance education and in the classroom setting.

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DOI: 10.3217/jucs-014-22-3627

Authors: Adriana Berlanga, Francisco García-Peñalvo

Abstract: After more than ten years of research aiming at defining methods and techniques to deliver personalized instruction, Adaptive Educational Hypermedia Systems have not made the jump into real practice systems. Reasons for this include the complexity of their development, their use of exclusive methods for defining adaptivity and educational elements, and their lack of interoperation amongst courses and applications. A possible alternative to cope with these issues is using as a common notational method the IMS Learning Design specification. This paper attempts to bring AEHS and IMS LD closer to each other in order to define adaptivity behaviour. To this end, it outlines how IMS LD could be used to define personalization properties and adaptive techniques and, based on that, it proposes a component called Adaptive Learning Designs, and an authoring tool to create these components. Furthermore, the paper discusses the benefits and limitations of IMS LD to define adaptivity behaviour, and ends suggesting additional research lines.

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DOI: 10.3217/jucs-014-18-2998

Authors: Boris Chidlovskii, Loïc Lecerf

Abstract: We address the problems of structuring and annotation of layout-oriented documents.We model the annotation problems as the collective classification on graph-like structures with typed instances and links that capture the domain-specific knowledge. We use the relational de-pendency networks (RDNs) for the collective inference on the multi-typed graphs. We then describe a variant of RDNs where a stacked approximation replaces the Gibbs sampling in orderto accelerate the inference. We report results of evaluation tests for both the Gibbs sampling and stacking inference on two document structuring examples.

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DOI: 10.3217/jucs-014-18-2982

Authors: Farshideh Einsele, Rolf Ingold, Jean Hennebert

Abstract: In this paper, we introduce and evaluate a system capable of recognizing words extracted from ultra low resolution images such as those frequently embedded on web pages. The design of the system has been driven by the following constraints. First, the system has to recognize small font sizes between 6-12 points where anti-aliasing and resampling filters are applied. Such procedures add noise between adjacent characters in the words and complicate any a priori segmentation of the characters. Second, the system has to be able to recognize any words in an open vocabulary setting, potentially mixing different languages in Latin alphabet. Finally, the training procedure must be automatic, i.e. without requesting to extract, segment and label manually a large set of data. These constraints led us to an architecture based on ergodic HMMs where states are associated to the characters. We also introduce several improvements of the performance increasing the order of the emission probability estimators, including minimum and maximum width constraints on the character models and a training set consisting all possible adjacency cases of Latin characters. The proposed system is evaluated on different font sizes and families, showing good robustness for sizes down to 6 points.

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DOI: 10.3217/jucs-014-18-2967

Authors: Daniel Pavelec, Luiz Oliveira, Edson Justino, Leonardo Batista

Abstract: Linguistics and stylistics have been investigated for author identification for quite awhile, but recently, we have testified a impressive growth in the volume with which lawyers and courts have called upon the expertise of linguists in cases of disputed authorship. This motivatescomputer science researchers to look to the problem of author identification from a different perspective. In this work, we propose a stylometric feature set based on conjunctions and ad-verbs of the Portuguese language to address the problem of author identification. Two different approaches of classification were considered. The first one is called writer-independent and it re-duces the pattern recognition problem to a single model and two classes, hence, makes it possible to build robust system even when few genuine samples per writer are available. The second oneis called the personal model, or writer-dependent, which very often performs better but needs a bigger number of samples per writer. Experiments on a database composed of short articlesfrom 30 different authors and Support Vector Machine (SVM) as classifier demonstrate that the proposed strategy can produced results comparable to the literature.

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DOI: 10.3217/jucs-014-17-2877

Authors: Craig Stewart

Abstract: The Cultural Artefacts in Education (CAE) questionnaire is used to determine the educational values of different cultures. In this paper I examine the results for ten countries, specifically focussing on their attitudes towards adaptive hypermedia in an educational setting. These results can inform the authoring process for adaptive systems & content, with Adaptive Hypermedia systems being able to employ stereotype adaptation to deliver content pre-adjusted to a learner’s cultural background.

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DOI: 10.3217/jucs-014-17-2859

Authors: Jesus Boticario, Olga Santos

Abstract: One of the key problems in developing standard based adaptive courses is the complexity involved in the design phase, especially when establishing the hooks for the dynamic modelling to be performed at runtime. This is particularly critical when the courses are based on adaptation-oriented learning scenarios, where the full eLearning cycle (design, publication, use and auditing) is considered. Based on the problems we experienced in developing such scenarios with a reusable, platform independent, objective-based approach in the aLFanet project we have established an alternative framework in the ADAPTAPlan project, which focuses on dynamically generating learning design templates with the support of user modelling, planning and machine learning techniques. In particular, in this paper we describe the problems we are tackling and how we are relaxing the design work by automatically building the IMS learning design of the course from a simplified set of data required from the course authors.

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DOI: 10.3217/jucs-014-17-2840

Authors: Roberto Arroyo, Miguel Gea, José Garrido, Pablo Haya, Rosa Carro

Abstract: Social-aware computing is an emerging trend based on ubiquitous computing technologies and collaborative work. A successful design demands a better understanding of group tasks, adaptation mechanisms and support for dynamic changes in a nomadic computing paradigm. This paper proposes the use of a hypermedia model to describe and support group activities in intelligent environments. The resulting system integrates adaptive context-aware information on the basis of user/group models in order to provide a structured access to dynamic task scheduling. In particular, we propose the use of the calendar metaphor as an ongoing connection between active spaces and collaborative tasks. This proposal provides the appropriate support for an easier human coordination to achieve common objectives in blended learning scenarios, and thus, extending authoring social tasks to physical spaces.

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DOI: 10.3217/jucs-014-16-2699

Authors: Myriam Arrue, Markel Vigo, Julio Abascal

Abstract: The aim of this paper is to review the best known methodologies for web applications development as well as the existing supporting tools and techniques from an accessibility-centric perspective. To this end, a number of development methodologies with their respective characteristics are described: model-based methodologies, user-centred processes, usability engineering methodologies and accessibility engineering methodologies. Some of these methodologies are provided with specific supporting tools which facilitate the accomplishment of specified tasks. However, there are methodologies which are not supported by specific tools. Therefore, web developers must deal with diverse tools in order to perform the corresponding activities. In this context, the development of accessible web applications is even more difficult. This paper concludes that there is not currently a holistic development framework to be used throughout the whole development process. Our contribution relies on a set of tools that support the different phases of the process. Since these tools are developed upon a common methodological basis, a high rate of interoperability is obtained. This cohesion allows their integration in a comprehensive framework so that the development of accessible web applications is facilitated.

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DOI: 10.3217/jucs-014-13-2239

Authors: Juan Preciado, Marino Linaje, Fernando Sánchez-Figueroa

Abstract: The development of Web applications, both functionality and Web User Interfaces (UIs), has been facilitated over the last few years using Web models and methodologies. However, new requirements that overcome traditional HTML-based Web 1.0 User Interfaces limits have arisen. Developers and tool vendors have answered these limits introducing Rich Internet Applications (RIAs). RIA technologies provide Web 2.0 UI capabilities such as high interactivity and native multimedia support among others. Currently, numerous developers are adapting many of their legacy Web 1.0 applications to Web 2.0 introducing Web 2.0 UI capacities while maintaining the business logic. Nevertheless, there is a lack of methodologies to support this adaptation process. In this paper we show how to use a model driven method called RUX-Method for the systematic adaptation of existing Web 1.0 UIs to Web 2.0 multidevice UIs. This method focuses on new UI capabilities provided by RIAs while taking advantage of functionality already provided by existing Web models. The proposal follows a common UI design for all the devices and an ad-hoc design approach for each device attending to its specific features.

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DOI: 10.3217/jucs-014-11-1911

Authors: Dawn Gregg

Abstract: There are many challenges developers face when attempting to reliably extract data from the Web. One of these challenges is the resilience of the extraction system to changes in the web pages information is being extracted from. This article compares the resilience of information extraction systems that use position based extraction with an ontology based extraction system and a system that combines position based extraction with ontology based extraction. The findings demonstrate the advantages of using a system that combines multiple extraction techniques, especially in environments where web sites change frequently and where data collection is conducted over an extended period of time.

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DOI: 10.3217/jucs-014-11-1893

Authors: Jinbeom Kang, Joongmin Choi

Abstract: As web sites are getting more complicated, the construction of web information extraction systems becomes more troublesome and time-consuming. A common theme is the difficulty in locating the segments of a page in which the target information is contained, which we call the informative blocks. This article reports on the Recognising Informative Page Blocks algorithm (RIPB), which is able to identify the informative block in a web page so that information extraction algorithms can work on it more efficiently. RIPB relies on an existing algorithm for vision-based page block segmentation to analyse and partition a web page into a set of visual blocks, and then groups related blocks with similar content structures into block clusters by using a tree edit distance method. RIPB recognises the informative block cluster by using tree alignment and tree matching. A series of experiments were performed, and the conclusions were that RIPB was more than 95% accurate in recognising informative block clusters, and improved the efficiency of information extraction by 17%.

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DOI: 10.3217/jucs-014-10-1763

Authors: Abdelhak Aqqal, Christoph Rensing, Ralf Steinmetz, Najib Elkamoun, Abdelghafour Berraissoul

Abstract: Recently Web Based Training (WBT) starts to be widely used as a new way of teaching. Unfortunately, this mode of teaching imposes new requirements and constraints. It has made the creation of learning material a complex and demanding task for the instructors as it takes much time and demands a multitude of skills, in particular technical skills that must be developed and continuously updated. Hence, we propose a collaborative authoring methodology based on division of labour as a way to produce WBTs where the processes of production are clearly separated to meet the existing and needed skills of persons involved in WBT production. This paper presents an efficient method to support instructor’s guidance during the first phase of the WBT production called the Macro Design using the Rhetorical Structure Theory (RST) and the taxonomies we developed.

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DOI: 10.3217/jucs-014-10-1717

Authors: Peng Han, Gerd Kortemeyer, Bernd Krämer, Christine Prümmer

Abstract: Although immense efforts have been invested in the construction of hundreds of learning object repositories, the degree of reuse of learning resources maintained in such repositories is still disappointingly low. As the reasons for this observation are not well understood, we carried out an empirical investigation with the objectives to identify recurring patterns in the retrieval and (re-) use of learning resources and to design and test social networking functionality supporting communities of practice. The outcomes of this project, which are reported here, aim to affect the design of a new generation of learning object repositories, like CampusContent, that tries to eliminate deficits of current repositories and involve recent contributions in the area of social software. Object of our investigation was LON-CAPA, a crossinstitutional learning content management and assessment system used since 2000. We analyzed hundreds of thousands of log data collected over a period of three years and detected various kinds of latent relationships among LON-CAPA users, such as the co-occurrence of learning resources from independent authors in instructional materials. To understand the rationale behind these findings, we conducted a study with LON-CAPA users. One section of the questionnaire asked for people's opinion about the expected benefit of community support. Nearly 80% of the study participants said that the formation of communities of practice (CoP) would be an asset to LON-CAPA. More than 80% would be ready to provide their profiles for matching up with CoPs and serve the community by spending time on the evaluation of resources they had used. Finally we sketch a faceted search functionality we designed to support CoPs among LON-CAPA users. This functionality is currently tested with two CoPs.

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DOI: 10.3217/jucs-014-02-0237

Authors: Luiz Oliveira, Edson Justino, Robert Sabourin, Flávio Bortolozzi

Abstract: In this work we present a strategy for off-line signature verification. It takes intoaccount a writer-independent model which reduces the pattern recognition problem to a 2-class problem, hence, makes it possible to build robust signature verification systems even when fewsignatures per writer are available. Receiver Operating Characteristic (ROC) curves are used to improve the performance of the proposed system . The contribution of this paper is two-fold. First of all, we analyze the impacts of choosing different fusion strategies to combine the partial decisions yielded by the SVM classifiers. Then ROC produced by different classifiers are combined using maximum likelihood analysis, producingan ROC combined classifier. Through comprehensive experiments on a database composed of 100 writers, we demonstrate that the ROC combined classifier based on the writer-independentapproach can reduce considerably false rejection rate while keeping false acceptance rates at acceptable levels.

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DOI: 10.3217/jucs-013-10-1471

Authors: Chunguo Wu, Maurizio Marchese, Jingqing Jiang, Alexander Ivanyukovich, Yanchun Liang

Abstract: With the currently growing interest in the Semantic Web, keywords/metadata extraction is coming to play an increasingly important role. Keywords extraction from documents is a complex task in natural languages processing. Ideally this task concerns sophisticated semantic analysis. However, the complexity of the problem makes current semantic analysis techniques insufficient. Machine learning methods can support the initial phases of keywords extraction and can thus improve the input to further semantic analysis phases. In this paper we propose a machine learning-based keywords extraction for given documents domain, namely scientific literature. More specifically, the least square support vector machine is used as a machine learning method. The proposed method takes the advantages of machine learning techniques and moves the complexity of the task to the process of learning from appropriate samples obtained within a domain. Preliminary experiments show that the proposed method is capable to extract keywords from the domain of scientific literature with promising results.

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DOI: 10.3217/jucs-013-10-1462

Authors: Chaoyong Wang, Yanfeng Sun, Yanchun Liang

Abstract: A novel support vector machine method for classification is presented in this paper. A modified kernel function based on the similarity metric and Riemannian metric is applied to the support vector machine. In general, it is believed that the similarity of homogeneous samples is higher than that of inhomogeneous samples. Therefore, in Riemannian geometry, Riemannian metric can be used to reflect local property of a curve. In order to enlarge the similarity metric of the homogeneous samples or reduce that of the inhomogeneous samples in the feature space, Riemannian metric is used in the kernel function of the SVM. Simulated experiments are performed using the databases including an artificial and the UCI real data. Simulation results show the effectiveness of the proposed algorithm through the comparison with four typical kernel functions without similarity metric.

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DOI: 10.3217/jucs-013-09-1354

Authors: Jin Yang, Tao Li, Sunjun Liu, Tiefang Wang, Diangang Wang, Gang Liang

Abstract: The current computer forensics approaches mainly focus on the network actions capture and analysis the evidences after attacks, which always result in the static methods. Inspired by the theory of artificial immune systems (AIS ), a novel model of Computer Forensics System is presented. The concepts and formal definitions of immune cells are given, and dynamically evaluative equations for self, antigen, immune tolerance, mature-lymphocyte lifecycle and immune memory are presented, and the hierarchical and distributed management framework of the proposed model are built. Furthermore, the idea of biology immunity is applied for enhancing the self-adapting and self-learning ability to adapt continuously variety environments. The experimental results show that the proposed model has the features of real-time processing, selfadaptively, thus providing a promising solution for computer forensics.

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DOI: 10.3217/jucs-013-01-0032

Authors: Farid Jaddi, Béatrice Paillassa

Abstract: Numerous studies have shown the difficulty for a single routing protocol to scale with respect to mobility and network size in wireless ad hoc networks. This paper presents a cluster-based extension of the DSR protocol called Cluster Source Routing (CSR)1. The proposed approach improves the scalability of DSR in high-density and low-mobility networks. The originality of our proposal is an adaptive use of DSR and CSR routing modes according to network density and node mobility in order to produce less overhead and perform efficient routing. Indeed, adaptation is a key feature for a routing protocol since network dynamics can suddenly and widely change in wireless ad hoc networks. Thus, the DSR-CSR protocol achieves enhanced performance over a broader {network density, node mobility} domain as shown by simulations.

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DOI: 10.3217/jucs-012-09-1208

Authors: Pawel Gocek, Michael Hartmann, Heinz Schleusener

Abstract: The internet is an unlimited growing and most comfortable information and communication base. In this context, web portals on the internet play an important role created for combining communication facilities and information data bases. An increasing number of portals involve web-based map applications to integrate geographic information for the representation of economical and other records. Web-based map applications are typically designed in a client-server architecture. Different solutions exist using especially HTML and JavaScript, Flash or Java applets. We discuss these possibilities and point out an alternative solution. Particularly, we show how to use Java Applet Technology and Asynchronous JavaScript and XML (Ajax) in this field. Finally, we report about our results as a complete, flexible map service solution which is available on the internet. An adapted kind of solution will be used by a geo-based marketing portal for offering information about the economic situation, social and cultural aspects and natural facts of regions to support joint-ventures inside the European Union.

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DOI: 10.3217/jucs-011-09-1555

Authors: Miguel A. Vega-Rodríguez, Juan Gómez-Pulido, Juan Sánchez-Pérez

Abstract: ICT (Information and Communication Technologies) are a very important educational resource at the present time because they allow place and time limitations to be overcome and therefore reduce costs. In addition, multimedia applications offer a set of characteristics in order to improve learning by means of interactive activities. For these reasons, we believe it is important to devote efforts to the development of proposals and prototypes for teaching via Internet. Since 1998, our research group has been focused on this objective and working on diverse projects such as SD2I, TEDA or PDIWeb. In this paper we overview all these projects, presenting a general description of each web platform, as well as the tools and methods used for their implementation. This paper also includes the results obtained after the use of each platform and the feedback from surveys. In this way, several conclusions are presented in the last section of this paper.

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DOI: 10.3217/jucs-011-03-0410

Authors: Andre Köhler, Frank Fuchs-Kittowski

Abstract: This article aims at the integration of communities of practice into work processes. Linear structures are often inappropriate for the execution of knowledge intensive tasks and work processes. The latter are characterized by non-linear sequences and dynamic, social interaction. But for the work in communities of practice the leading path, that is needed for structuring the work, is often missing. Our article exposes the requirements in order to integrate the dynamic, social processes of the knowledge generation in communities of practice with formal described knowledge intensive processes. For the support of communities the Wiki-concept is introduced. In order to integrate communities into process structures a concept for an appropriate interface is presented. On the basis of this interface concept an information retrieval algorithm is used to connect the process-oriented structures with community-oriented structures. The prototype realisation of this concept is shown by a short example.

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DOI: 10.3217/jucs-011-02-0250

Authors: Janusz Sobecki

Abstract: Consensus methods proved to be very effective in solving problems in many areas. In this paper a hybrid adaptation of web-based system user interfaces that us es consensus methods is presented. The hybrid recommendation is a combination of the following methods: demographic, content-based, and collaborative. Each of this meth od has its specific advantages and disadvantages. The hybrid adaptation enables over coming disadvantages of each separate solution.

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DOI: 10.3217/jucs-011-02-0213

Authors: Jason Jung

Abstract: With the exponentially increasing amount of information available on the World Wide Web, users have b een getting more difficult to seek relevant information. Several studies have been conducted on the concept of adaptive approaches, in which the user s personal interests are taken into account. In this paper, we propose a user-support mechanism based on the sharing of knowledge with other users through the collaborative Web browsing, focusing specifically on the user s interests extracted from his or her own bookmarks. Simple URL based boo kmarks are endowed with semantic and structural information through the conceptualization based on ontology. In order to deal with the dynamic usage of bookmarks, ontology learning based on a hierarchical clustering method can be exploited. This system is composed of a facilitator agent and multiple personal agents. In experiments conducted with this system, it was found that approximately 53.1% of the total time was saved during collaborat ive browsing for the purpose of seeking the equivalent set of information, as compared with normal personal Web browsing.

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DOI: 10.3217/jucs-010-08-1014

Authors: Emmanuel Zenou, Manuel Samuelides

Abstract: This paper presents an original application of the Galois lattice theory, the visual landmark selection for topological localization of an autonomous mobile robot, equipped with a color camera. First, visual landmarks have to be selected in order to characterize a structural environment. Second, such landmarks have to be detected and updated for localization. These landmarks are combinations of attributes, and the selection process is done through a Galois lattice. This paper exposes the landmark selection process and focuses on probabilistic landmarks, which give the robot thorough information on how to locate itself. As a result, landmarks are no longer binary, but probabilistic. The full process of using such landmarks is described in this paper and validated through a robotics experiment.

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DOI: 10.3217/jucs-010-08-0985

Authors: Claudio Carpineto, Giovanni Romano

Abstract: The recent advances in Formal Concept Analysis (FCA) together with the major changes faced by modern Information Retrieval (IR) provide new unprecedented challenges and opportunities for FCA-based IR applications. The main advantage of FCA for IR is the possibility of creating a conceptual representation of a given document collection in the form of a document lattice, which may be used both to improve the retrieval of specific items and to drive the mining of the collection's contents. In this paper, we will examine the best features of FCA for solving IR tasks that could not be easily addressed by conventional systems, as well as the most critical aspects for building FCA-based IR applications. These observations have led to the development of CREDO, a system that allows the user to query Web documents and see retrieval results organized in a browsable concept lattice. This is the second major focus of the paper. We will show that CREDO is especially useful for quickly locating the documents corresponding to the meaning of interest among those retrieved in response to an ambiguous query, or for mining the contents of the documents that reference a given entity. An on-line version of the system is available for testing at http://credo.fub.it.

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DOI: 10.3217/jucs-010-03-0252

Authors: Koichi Hori, Kumiyo Nakakoji, Yasuhiro Yamamoto, Jonathan Ostwald

Abstract: Our research on knowledge management is rooted in the community perspective. We believe that knowledge systems should serve primarily to help people create and share new knowledge. But we also acknowledge the role of stable, structured and reliable information, both as a component of our systems and as a component of the organizations within which we work. The contribution of the paper is a framework for integrating organizational and community perspectives on knowledge management and its computational support. Our basic idea is that knowledge is not a static chunk of information, but rather, knowledge evolves in a cycle of knowledge liquidization and crystallization. The evolving process takes place through the interactions among conceptual worlds, representational worlds, and the real world. This paper first describes the knowledge liquidization and crystallization framework. We then illustrate the approach with three systems, Knowledge Nebula Crystallizer, livingOM, and ART-SHTA.

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DOI: 10.3217/jucs-009-12-1428

Authors: Cord Hockemeyer, Owen Conlan, Vincent Wade, Dietrich Albert

Abstract: Several approaches for formalising prerequisite structures on skills or competencies based on the psychological theory of knowledge space have been suggested and applied for adaptive eLearning. In this paper, we will discuss how these structures may be applied in skill management in a broader sense. After introducing some formal structures for prerequisite relationships between competencies, we will briefly present an example of an adaptive eLearning system based on this approach (APeLS). Several other aspects of the system which promise to be useful for advanced skill management are discussed. In the final part of this paper, we will discuss such broader applications of the model with respect to personal as well as to organisational skill management.

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DOI: 10.3217/jucs-009-07-0596

Authors: Elisabeth Kamentz, Christa Womser-Hacker

Abstract: In our study we set the goal to consider culture as a crucial factor of learning system design. This culture oriented approach is put in concrete terms by comparing US-American and German learning programs on four different levels: layout, interaction and navigation, presentation of content, and the didactic approach. The results of a questioning on culturally specific approaches to computers complete this investigation.

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DOI: 10.3217/jucs-009-06-0520

Authors: Raphael Volz, Rudi Studer, Alexander Maedche, Boris Lauser

Abstract: We present a novel approach of extracting a domain ontology from large-scale thesauri. Concepts are identified to be relevant for a domain based on their frequent occurrence in domain texts. The approach allows to bootstrap the ontology engineering process from given legacy thesauri and identifies an initial domain ontology that may easily be refined by experts in a later stage. We present a thorough evaluation of the results obtained in building a biosecurity ontology for the UN FAO AOS project.

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DOI: 10.3217/jucs-008-10-0957

Authors: Gisbert Dittrich

Abstract: To use hypertext/hypermedia elements in teaching at universities an author not only needs knowledge of the technological possibilities. In addition he/she has to renew a here so called mental model of the relevant aspects of the material to be transferred. For the author, this last mentioned problem seems to be a central and often very complicated and time consuming one.

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DOI: 10.3217/jucs-008-10-0924

Authors: Alexander Mehler

Abstract: On the background of rising Intranet applications the automatic generation of adaptable, context-sensitive hypertexts becomes more and more important [El-Beltagy et al., 2001]. This observation contradicts the literature on hypertext authoring, where Information Retrieval techniques prevail, which disregard any linguistic and context-theoretical underpinning. As a consequence, resulting hypertexts do not manifest those schematic structures, which are constitutive for the emergence of text types and the context-mediated understanding of their instances, i.e. natural language texts. This paper utilizes Systemic Functional Linguistics (SFL) and its context model as a theoretical basis of hypertext authoring. So called Systemic Functional Hypertexts (SFHT) are proposed, which refer to a stratified context layer as the proper source of text linkage. The purpose of this paper is twofold: First, hypertexts are reconstructed from a linguistic point of view as a kind of supersign, whose constituents are natural language texts and whose structuring is due to intra- and intertextual coherence relations and their context-sensitive interpretation. Second, the paper prepares a formal notion of SFHTs as a first step towards operationalization of fundamental text linguistic concepts. On this background, SFHTs serve to overcome the theoretical poverty of many approaches to link generation.

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DOI: 10.3217/jucs-008-10-0913

Authors: Erich Gams, Siegfried Reich

Abstract: Being lost in space and overloaded with information are two key problems users are confronted with, when searching for appropriate information. Trails built from information about the users' browsing paths and activities, are an established approach to assist users in navigating vast information spaces. However, existing trail-based systems are focusing on browsers only and therefore do not fully exploit the notion of trails. The TrailTRECer framework addresses these issues by being open to any application and any activity. The usability of the framework and the concept of user trails were tested by building a navigation support system with different trail-enabled clients.

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DOI: 10.3217/jucs-008-10-0881

Authors: Volker Mattick

Abstract: Design for All is an important challenge for hypermedia engineering. We analyze this challenge and show that it is necessary to find a way of describing partially designed hypermedia documents that can then be transformed into different hypermedia applications according to user needs and call this concept "semi-documents". We sketch similarities and differences to existing formalisms and conclude that there are three areas in which functional languages can make a contribution: the development of an embedded special-purpose language for describing semi-documents, the building of generators which produce hypermedia applications from semi-document, and the realization of support tools for the development of semi-documents.

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DOI: 10.3217/jucs-008-10-0871

Authors: David Hicks, Uffe Wiil, Peter Nürnberg

Abstract: Structural computing is one of the most recent research threads to emerge in the field of hypermedia. Though a relatively new line of study, research results have already started to emerge in the structural computing field. This paper examines a number of structural computing research projects to provide an overview of the current state of the field as well as a look at the direction of ongoing projects. It also briefly discusses additional areas of research in structural computing that will be important to consider as research in the field continues.

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