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The computational complexity of universality problems for prefixes, suffixes, factors, and subwords of regular languages (0907.0159v3)
Published 1 Jul 2009 in cs.FL and cs.CC
Abstract: In this paper we consider the computational complexity of the following problems: given a DFA or NFA representing a regular language L over a finite alphabet Sigma is the set of all prefixes (resp., suffixes, factors, subwords) of all words of L equal to Sigma*? In the case of testing universality for factors of languages represented by DFA's, we find an interesting connection to Cerny's conjecture on synchronizing words.