Decidability of DPDA equivalence

Decidability of DPDA equivalence

A proof of decidability of equivalence between deterministic pushdown automata is presented using a mixture of methods developed in concurrency and language theory. The technique appeals to a tableau proof system for equivalence of configurations of strict deterministic grammars.

An Introduction to Decidability of DPDA Equivalence

A Short Decidability Proof for DPDA Language Equivalence via First-Order Grammars

The main aim of the paper is to give a short self-contained proof of the decidability of language equivalence for deterministic pushdown automata, which is the famousproblem solved by G. Sénizergues, for which C. Stirling has derived a primitive recursive complexity upper bound. The proof here is given in the framework of first-order grammars, which seems to be particularly apt for the aim.

Deciding DPDA Equivalence Is Primitive Recursive

Recently Sénizergues showed decidability of the equivalence problem for deterministic pushown automata. The proof of decidability is two semi-decision procedures that do not give a complexity upper bound for the problem. Here we show that there is a simpler deterministic decision procedure that has a primitive recursive upper bound.

Decidability of Split Equivalence

We show that the following problem is decidable: given expressions E1 and E2 constructed from variables by the regular operations and shuffle, is the identity E1 = E2 true for all instantiations of its variables by strings? Our proof uses the notations developed in the causal approach to concurrency. As a byproduct we obtain decidability of similar equivalence for other formalisms. In particula...