Treatment of $\epsilon$-Moves in Subset Construction

Gertjan van Noord
Alfa-informatica & BCN
vannoord@let.rug.nl
Rijksuniversiteit Groningen

Abstract:

The paper discusses the problem of determinising finite-state automata containing large numbers of $\epsilon$-moves. Experiments with finite-state approximations of natural language grammars often give rise to very large automata with a very large number of $\epsilon$-moves. The paper identifies three subset construction algorithms which treat $\epsilon$-moves. A number of experiments has been performed which indicate that the algorithms differ considerably in practice. Furthermore, the experiments suggest that the average number of $\epsilon$-moves per state can be used to predict which algorithm is likely to perform best for a given input automaton.