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  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher-id">109</journal-id>
      <journal-id journal-id-type="index">urn:lsid:arphahub.com:pub:3dc5f44e-8666-58db-bc76-a455210e8891</journal-id>
      <journal-title-group>
        <journal-title xml:lang="en">JUCS - Journal of Universal Computer Science</journal-title>
        <abbrev-journal-title xml:lang="en">jucs</abbrev-journal-title>
      </journal-title-group>
      <issn pub-type="ppub">0948-695X</issn>
      <issn pub-type="epub">0948-6968</issn>
      <publisher>
        <publisher-name>Journal of Universal Computer Science</publisher-name>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="doi">10.3217/jucs-002-03-0097</article-id>
      <article-id pub-id-type="publisher-id">27223</article-id>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Research Article</subject>
        </subj-group>
        <subj-group subj-group-type="scientific_subject">
          <subject>F.1.3 - Complexity Measures and Classes</subject>
          <subject>F.2 - ANALYSIS OF ALGORITHMS AND PROBLEM COMPLEXITY</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>An Optimal Parallel Algorithm for Learning DFA</article-title>
      </title-group>
      <contrib-group content-type="authors">
        <contrib contrib-type="author" corresp="yes">
          <name name-style="western">
            <surname>Balcázar</surname>
            <given-names>José L.</given-names>
          </name>
          <email xlink:type="simple">balqui@lsi.upc.es</email>
          <xref ref-type="aff" rid="A1">1</xref>
        </contrib>
        <contrib contrib-type="author" corresp="no">
          <name name-style="western">
            <surname>Díaz</surname>
            <given-names>Josep</given-names>
          </name>
          <xref ref-type="aff" rid="A1">1</xref>
        </contrib>
        <contrib contrib-type="author" corresp="no">
          <name name-style="western">
            <surname>Gavaldà</surname>
            <given-names>Ricard</given-names>
          </name>
          <xref ref-type="aff" rid="A1">1</xref>
        </contrib>
        <contrib contrib-type="author" corresp="no">
          <name name-style="western">
            <surname>Watanabe</surname>
            <given-names>Osamu</given-names>
          </name>
          <xref ref-type="aff" rid="A2">2</xref>
        </contrib>
      </contrib-group>
      <aff id="A1">
        <label>1</label>
        <addr-line content-type="verbatim">Universitat Politècnica de Catalunya, , Spain</addr-line>
        <institution>Universitat Politècnica de Catalunya</institution>
        <country>Spain</country>
      </aff>
      <aff id="A2">
        <label>2</label>
        <addr-line content-type="verbatim">Tokyo Institute of Technology, , Japan</addr-line>
        <institution>Tokyo Institute of Technology</institution>
        <country>Japan</country>
      </aff>
      <author-notes>
        <fn fn-type="corresp">
          <p>Corresponding author: José L. Balcázar (<email xlink:type="simple">balqui@lsi.upc.es</email>).</p>
        </fn>
        <fn fn-type="edited-by">
          <p>Academic editor: </p>
        </fn>
      </author-notes>
      <pub-date pub-type="collection">
        <year>1996</year>
      </pub-date>
      <pub-date pub-type="epub">
        <day>28</day>
        <month>03</month>
        <year>1996</year>
      </pub-date>
      <volume>2</volume>
      <issue>3</issue>
      <fpage>97</fpage>
      <lpage>112</lpage>
      <uri content-type="arpha" xlink:href="http://openbiodiv.net/01A45ADF-BF75-5B95-9B50-48D4A2C48734">01A45ADF-BF75-5B95-9B50-48D4A2C48734</uri>
      <uri content-type="zenodo_dep_id" xlink:href="https://zenodo.org/record/6995204">6995204</uri>
      <permissions>
        <copyright-statement>José L. Balcázar, Josep Díaz, Ricard Gavaldà, Osamu Watanabe</copyright-statement>
        <license license-type="creative-commons-attribution" xlink:href="" xlink:type="simple">
          <license-p>This article is freely available under the J.UCS Open Content License.</license-p>
        </license>
      </permissions>
      <abstract>
        <label>Abstract</label>
        <p>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).</p>
      </abstract>
    </article-meta>
  </front>
</article>
