We consider a pushdown automaton as a word-rewriting system with labelled rules applied only in a prefix way. The notion of pushdown transition graph is then extended to the notion of prefixâ€¦ (More)

We deene a family of graphs whose monadic theory is (in linear space) reducible to the monadic theory S2S of the complete ordered binary tree. This family contains strictly the context-free graphsâ€¦ (More)

We study a transformation on terms consisting of applying an inverse deterministic rational mapping followed by an unfolding. Iterating these transformations from the regular terms gives a hierarchyâ€¦ (More)

We present an elementary algorithm for deciding bisimulation equivalence between arbitrary context-free processes. This improves on the state of the art algorithm of Christensen, H uttel and Stirlingâ€¦ (More)

We consider the factorization (collapse) of infinite transition graphs wrt. bisimulation equivalence. It turns out that almost none of the more complex classes of the process taxonomy, which has beenâ€¦ (More)

Deterministic graph grammars are finite devices which generate the transition graphs of pushdown automata. We define the notion of synchronization by grammars, generalizing previous sub-classes suchâ€¦ (More)

Context-free grammars are one of the most classical and fundamental notions in computer science textbooks, in both theoretical and applied settings. As characterizations of the well-known class ofâ€¦ (More)