Witold Charatonik

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Set constraints are inclusions between expressions denoting sets of trees. The eficiency of their satisfiabili ty test is a central issue in set-based program analysis, their main application domain. W e introduce the class of set constraints with intersection (the only operators forming the expressions are constructors and intersection) and show that i ts(More)
We consider the two-variable logic with counting quantifiers (C<sup>2</sup>) interpreted over finite structures that contain two forests of ranked trees. This logic is strictly more expressive than standard C<sup>2</sup> and it is no longer a fragment of first-order logic. In particular, it can express that a structure is a ranked tree, a cycle, or a(More)
We settle the complexity bounds of the model checking problem for the ambient calculus with public names against the ambient logic. We show that if either the calculus contains replication or the logic contains the guarantee operator, the problem is undecidable. In the case of the replication-free calculus and guarantee-free logic we prove that the problem(More)
Systems of set constraints describe relations between sets of ground terms. They have been successfully used in program analysis and type inference. So far two proofs of decidability of mixed set constraints have been given: However, both these proofs are long, involved and do not seem to extend to more general set constraints. Our approach is based on a(More)
We study the control reachability problem in the Dolev-Yao model of cryptographic protocols when principals are represented by tail recursive processes with generated names. We propose a conservative approximation of the problem by reduction to a non-standard collapsed operational semantics and we introduce checkable syntactic conditions entailing the(More)