Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
CIAA '00 Revised Papers from the 5th International Conference on Implementation and Application of Automata
Obtaining shorter regular expressions from finite-state automata
Theoretical Computer Science
Enumeration and generation with a string automata representation
Theoretical Computer Science
Regular expressions: new results and open problems
Journal of Automata, Languages and Combinatorics
Improved Approximation Algorithms for Minimum Weight Vertex Separators
SIAM Journal on Computing
Finite Automata, Digraph Connectivity, and Regular Expression Size
ICALP '08 Proceedings of the 35th international colloquium on Automata, Languages and Programming, Part II
Provably Shorter Regular Expressions from Deterministic Finite Automata
DLT '08 Proceedings of the 12th international conference on Developments in Language Theory
Complexity measures for regular expressions
Journal of Computer and System Sciences
The effect of rewriting regular expressions on their accepting automata
CIAA'03 Proceedings of the 8th international conference on Implementation and application of automata
Optimal lower bounds on regular expression size using communication complexity
FOSSACS'08/ETAPS'08 Proceedings of the Theory and practice of software, 11th international conference on Foundations of software science and computational structures
Approximation to the smallest regular expression for a given regular language
CIAA'04 Proceedings of the 9th international conference on Implementation and Application of Automata
The language, the expression, and the (small) automaton
CIAA'05 Proceedings of the 10th international conference on Implementation and Application of Automata
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We continue our work [H. Gruber, M. Holzer: Provably shorter regular expressions from deterministic finite automata (extended abstract). In Proc. DLT , LNCS 5257, 2008] on the problem of finding good elimination orderings for the state elimination algorithm, one of the most popular algorithms for the conversion of finite automata into equivalent regular expressions. Here we tackle this problem both from the theoretical and from the practical side. First we show that the problem of finding optimal elimination orderings can be used to estimate the cycle rank of the underlying automata. This gives good evidence that the problem under consideration is difficult, to a certain extent. Moreover, we conduct experiments on a large set of carefully chosen instances for five different strategies to choose elimination orderings, which are known from the literature. Perhaps the most surprising result is that a simple greedy heuristic by [M. Delgado, J. Morais: Approximation to the smallest regular expression for a given regular language. In Proc. CIAA , LNCS 3317, 2004] almost always outperforms all other strategies, including those with a provable performance guarantee.