On characterization of fuzzy tree pushdown automata

This paper introduces the concepts of fuzzy tree pushdown automata and fuzzy context-free tree grammars. At first, we show that any fuzzy context-free tree grammar can be converted into a corresponding definition of fuzzy Chomsky normal form for trees. Then, the relation between a fuzzy context-free tree grammar and a fuzzy tree pushdown automaton is investigated. In fact, we show that the class of languages accepted by fuzzy tree pushdown automata is identical to the one generated by fuzzy context-free tree grammars. Some examples are given to clarify the results.