Parameterized regular expressions and their languages
نویسندگان
چکیده
منابع مشابه
Parameterized Regular Expressions and Their Languages
We study regular expressions that use variables, or parameters, which are interpreted as alphabet letters. We consider two classes of languages denoted by such expressions: under the possibility semantics, a word belongs to the language if it is denoted by some regular expression obtained by replacing variables with letters; under the certainty semantics, the word must be denoted by every such ...
متن کاملEnumerating Regular Expressions and Their Languages
In this chapter we discuss the problem of enumerating distinct regular expressions bysize and the regular languages they represent. We discuss various notions of the size of a regularexpression that appear in the literature and their advantages and disadvantages. We consider aformal definition of regular expressions using a context-free grammar.We then show how to enumerate stri...
متن کاملOn Nilpotent Languages and Their Characterization by Regular Expressions
Tree languages recognized by deterministic root-to-frontier recognizers are also called DR-languages. The concept of generalized R-chain languages was introduced by the author in his paper On monotone languages and their characterization by regular expressions (Acta Cybernetica, 18 (2007), 117134.) and it has turned out that the monotone DR-languages are exactly those languages that can be give...
متن کاملSimple-Regular Expressions and Languages
We define simple-regular expressions and languages. Simple-regular languages provide a necessary condition for a language to be outfix-free. We design algorithms that compute simple-regular languages from finite-state automata. Furthermore, we investigate the complexity blowup from a given finite-state automaton to its simple-regular language automaton and show that there is an exponential blow...
متن کاملOn monotone languages and their characterization by regular expressions
In one of their papers, F. Gécseg and B. Imreh gave a characterization for monotone string languages by regular expressions. It has turned out that the monotone string languages are exactly those languages that can be represented by finite unions of seminormal chain languages. In this paper a similar characterization is given for monotone DR-languages.
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2013
ISSN: 0304-3975
DOI: 10.1016/j.tcs.2012.12.036