Nondeterministic fuzzy automata with membership values in complete residuated lattices

Automata theory based on complete residuated lattice-valued logic has been initiated by Qiu, and further systematically established by Qiu et al. In this paper, we propose the notion of nondeterministic fuzzy automata with membership values in a complete residuated lattice L, called lattice-valued nondeterministic fuzzy automata (L-NFAs). In our setting, a state of an L-NFA may have more than one transition labeled by the same input symbol, which reflects nondeterminism. To compare the behaviors of L-NFAs, we introduce two language equivalence relations which have different discriminating power. Furthermore, we extend the two relations to the complete residuated lattice-valued setting and investigate their properties such as robustness and compositionality. The theory developed here is applicable to the quantitative modeling and verification of fuzzy systems. (C) 2016 Elsevier Inc. All rights reserved.