We extend the Nelsonâ€“Oppen combination procedure to the case of theories that are compatible with respect to a common subtheory in the shared signature. The notion of compatibility relies on modelâ€¦ (More)

Sufficient syntactic conditions for canonicity in intermediate and intuitionistic modal logics are given. We present a new technique which does not require semantic first-order reduction and which isâ€¦ (More)

Most of the research on temporalized Description Logics (DLs) has concentrated on the case where temporal operators can be applied to concepts, and sometimes additionally to TBox axioms and ABoxâ€¦ (More)

We show that some common varieties of modal K4-algebras have nitary uni cation type, thus providing e ective best solutions for equations in free algebras. Applications to admissible inference rulesâ€¦ (More)

The safety of infinite state systems can be checked by a backward reachability procedure. For certain classes of systems, it is possible to prove the termination of the procedure and hence concludeâ€¦ (More)

In the context of combinations of theories with disjoint signatures, we classify the component theories according to the decidability of constraint satisfiability problems in arbitrary and inâ€¦ (More)

Every normal modal logic L gives rise to the consequence relation Ï† |=L Ïˆ which holds iff Ïˆ is true in a world of an L-model whenever Ï† is true in that world. We consider the following algorithmicâ€¦ (More)