Brzozowski type determinization for fuzzy automata

Abstract

In this paper we adapt the well-known Brzozowski determinization method to fuzzy automata. This method gives better results than all previously known methods for determinization of fuzzy automata developed by B\v{e}lohl\'avek [Inform Sciences 143 (2002) 205--209], Li and Pedrycz [Fuzzy Set Syst 156 (2005) 68--92], Ignjatovi\'c et al. [Inform Sciences 178 (2008) 164--180], and Jan\v{c}i\'c et al. [Inform Sciences 181 (2011) 1358--1368]. Namely, as in the case of ordinary nondeterministic automata, Brzozowski type determinization of a fuzzy automaton results in a minimal crisp-deterministic fuzzy automaton equivalent to the starting fuzzy automaton, and we show that there are cases when all previous methods result in infinite automata, while Brzozowski type determinization results in a finite one. The paper deals with fuzzy automata over complete residuated lattices, but identical results can also be obtained in a more general context, for fuzzy automata over lattice-ordered monoids, and even for weighted automata over commutative semirings.