Theory of ω-languagesI: Characterizations of ω-context-free languages
نویسندگان
چکیده
منابع مشابه
Topological Complexity of Context-Free ω-Languages: A Survey
We survey recent results on the topological complexity of context-free ω-languages which form the second level of the Chomsky hierarchy of languages of infinite words. In particular, we consider the Borel hierarchy and the Wadge hierarchy of non-deterministic or deterministic context-free ω-languages. We study also decision problems, the links with the notions of ambiguity and of degrees of amb...
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We determine completely the Borel hierarchy of the class of context free ω-languages, showing that, for each recursive non null ordinal α, there exist some Σα-complete and some Π 0 α-complete ω-languages accepted by Büchi 1-counter automata.
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We study the links between the topological complexity of an ω-context free language and its degree of ambiguity. In particular, using known facts from classical descriptive set theory, we prove that non Borel ω-context free languages which are recognized by Büchi pushdown automata have a maximum degree of ambiguity. This result implies that degrees of ambiguity are really not preserved by the o...
متن کاملDeterministic Fuzzy Automaton on Subclasses of Fuzzy Regular ω-Languages
In formal language theory, we are mainly interested in the natural language computational aspects of ω-languages. Therefore in this respect it is convenient to consider fuzzy ω-languages. In this paper, we introduce two subclasses of fuzzy regular ω-languages called fuzzy n-local ω-languages and Buchi fuzzy n-local ω-languages, and give some closure properties for those subclasses. We define a ...
متن کاملOperator Precedence ω-Languages
Recent literature extended the analysis of ω-languages from the regular ones to various classes of languages with “visible syntax structure”, such as visibly pushdown languages (VPLs). Operator precedence languages (OPLs), instead, were originally defined to support deterministic parsing and exhibit interesting relations with these classes of languages: OPLs strictly include VPLs, enjoy all rel...
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ژورنال
عنوان ژورنال: Journal of Computer and System Sciences
سال: 1977
ISSN: 0022-0000
DOI: 10.1016/s0022-0000(77)80004-4