Derivatives of rational expressions with multiplicity

This paper addresses the problem of turning a rational (i.e. regular) expression into a finite automaton. We formalize and generalize the idea of “ partial derivatives” introduced in 1995 by Antimirov, in order to obtain a construction of an automaton with multiplicity from a rational expression des...

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Veröffentlicht in:Theoretical computer science 2005-02, Vol.332 (1), p.141-177
Hauptverfasser: Lombardy, Sylvain, Sakarovitch, Jacques
Format: Artikel
Sprache:eng
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Zusammenfassung:This paper addresses the problem of turning a rational (i.e. regular) expression into a finite automaton. We formalize and generalize the idea of “ partial derivatives” introduced in 1995 by Antimirov, in order to obtain a construction of an automaton with multiplicity from a rational expression describing a formal power series with coefficients in a semiring. We first define precisely what is such a rational expression with multiplicity and which hypothesis should be put on the semiring of coefficients in order to keep the usual identities. We then define the derivative of such a rational expression as a linear combination of expressions called derived terms and we show that all derivatives of a given expression are generated by a finite set of derived terms, that yields a finite automaton with multiplicity whose behaviour is the series denoted by the expression. We also prove that this automaton is a quotient of the standard (or Glushkov) automaton of the expression. Finally, we propose and discuss some possible modifications to our definition of derivation.
ISSN:0304-3975
1879-2294
DOI:10.1016/j.tcs.2004.10.016