The tyft/tyxt format reduces to tree rules

Abstract

Groote and Vaandrager [5] introduced the tyft/tyxt format for transition system specifications (TSSs), and established that for each TSS in this format that is well-founded, the strong bisimulation it induces is a congruence. In this paper, we construct for each TSS in tyft/tyxt format an equivalent TSS that consists of tree rules only. As a corollary we can give an affirmative answer to an open question, namely whether the well-foundedness condition in the Congruence Theorem of [5] can be dropped. These results extend to tyft/tyxt with negative premises and predicates.