Approximation-based Tree Regular Model-Checking

This paper addresses the following general problem of tree regular model-checking: decide whether R * ( L ) ∩ L p = θ where R * is the reflexive and transitive closure of a successor relation induced by a term rewriting system R , and L and L p are both regular tree languages. We develop an automatic approximation-based technique to handle this - undecidable in general - problem in most practical cases, extending a recent work by Feuillade, Genet and Viet Triem Tong. We also make this approach fully automatic for practical validation of security protocols.