Edit-distance between visibly pushdown languages

Abstract

We study the edit-distance between two visibly pushdown languages. It is well-known that the edit-distance between two context-free languages is undecidable. The class of visibly pushdown languages is a robust subclass of context-free languages since it is closed under intersection and complementation whereas context-free languages are not. We show that the edit-distance problem is decidable for visibly pushdown languages and present an algorithm for computing the edit-distance based on the construction of an alignment PDA. Moreover, we show that the edit-distance can be computed in polynomial time if we assume that the edit-distance is bounded by a fixed integer k.