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<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.0 20120330//EN" "JATS-journalpublishing1.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article"><front><journal-meta><journal-id journal-id-type="publisher-id">INFORMATICA</journal-id><journal-title-group><journal-title>Informatica</journal-title></journal-title-group><issn pub-type="epub">0868-4952</issn><issn pub-type="ppub">0868-4952</issn><publisher><publisher-name>VU</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">INF8103</article-id><article-id pub-id-type="doi">10.3233/INF-1997-8103</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research article</subject></subj-group></article-categories><title-group><article-title>D-graphs in context-free language theory</article-title></title-group><contrib-group><contrib contrib-type="Author"><name><surname>Stanevičienė</surname><given-names>Larisa</given-names></name><email xlink:href="mailto:stanev@ccas.ru">stanev@ccas.ru</email><xref ref-type="aff" rid="j_INFORMATICA_aff_000"/></contrib><aff id="j_INFORMATICA_aff_000">Moscow State University, Department of Computational Mathematics and Cybernetics, Akademika Vargi 8–112, Moscow, Russia</aff></contrib-group><pub-date pub-type="epub"><day>01</day><month>01</month><year>1997</year></pub-date><volume>8</volume><issue>1</issue><fpage>43</fpage><lpage>56</lpage><abstract><p>The paper present a proposed approach in the context-free language theory. The main new notion is a graph defining a pushdown automaton (PDA). Each vertex of such graph is a pair (state, stack symbol). Each edge corresponds to a “command” and is labelled by input portion being read by the command and by a “charge” describing the stack word transformation. Some paths of the graph represent PDA's computations. The finite automata are a case of the pushdown graphs. The paper contains some of the author's results based on the approach – the notion of a D-language extending the notion of Dyck's language and the theorem on a representation of a context-free language as a morphical image of the intersection of a D-language with a local set.</p></abstract><kwd-group><label>Keywords</label><kwd>pushdown automata</kwd><kwd>graphic characterization of context-free languages</kwd><kwd>morphic characterization of context-free languages</kwd></kwd-group></article-meta></front></article>