One-Unambiguous Regular Languages
نویسندگان
چکیده
منابع مشابه
One-Unambiguous Regular Languages
The ISO standard for the Standard Generalized Markup Language (SGML) provides a syntactic meta-language for the definition of textual markup systems. In the standard, the right-hand sides of productions are based on regular expressions, although only regular expressions that denote words unambiguously, in the sense of the ISO standard, are allowed. In general, a word that is denoted by a regula...
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Separation is a classical problem asking whether, given two sets belonging to some class, it is possible to separate them by a set from a smaller class. We discuss the separation problem for regular languages. We give a Ptime algorithm to check whether two given regular languages are separable by a piecewise testable language, that is, whether a BΣ1(<) sentence can witness that the languages ar...
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Unambiguous automata are usually seen as a natural class of automata in-between deterministic and nondeterministic ones. We show that in case of infinite tree languages, the unambiguous ones are topologically far more complicated than the deterministic ones. We do so by providing operations that generate a family (Abα)α<φ2(0) of unambiguous automata such that: 1. It respects the strict Wadge or...
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Article history: Received 28 June 2007 Revised 18 February 2008 Available online 6 June 2008
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Non-terminally separated (NTS) languages are a subclass of deterministic context free languages where there is a stable relationship between the substrings of the language and the non-terminals of the grammar. We show that when the distribution of samples is generated by a PCFG, based on the same grammar as the target language, the class of unambiguous NTS languages is PAC-learnable from positi...
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ژورنال
عنوان ژورنال: Information and Computation
سال: 1998
ISSN: 0890-5401
DOI: 10.1006/inco.1997.2688