. A simple and elegant formulation of compositional proof systems for concurrent programs results from a refinement of temporal logic semantics. The refined temporal language we propose is closed under w- stuttering and, thus, provides a fully abstract semantics with respect to some chosen observation level w. This avoids incorporating irrelevant detail in the temporal semantics of parallel programs. Besides compositional verification, concurrent program design and implementation of a coarser-grained program by a finer-grained one, turn out to be easily practicable in the setting of the new temporal logic. 1 Introduction The regular temporal logic [14, 16] provides a powerful tool for global specification and non-compositional verification of existing concurrent programs. However, this logic offers a very poor support for modular specification and verification and, consequently, systematic design of concurrent programs is hard (if not impossible) to do in such a setting. The lack of ...

. A simple and elegant formulation of compositional proof systems for concurrent programs results from a refinement of temporal logic semantics. The refined temporal language we propose is closed under w-stuttering and, thus, provides a fully abstract semantics with respect to some chosen observation level w. This avoids incorporating irrelevant detail in the temporal semantics of parallel programs. Besides compositional verification, concurrent program design and implementation of a coarser-grained program by a finer-grained one, are easily practicable in the setting of the new temporal logic. 1 Introduction A well-known problem for the verification and the construction of concurrent programs is that specifications that would be satisfied by a given process viewed in isolation, might be invalidated by actions performed by other processes executing in parallel. Composition principles provide a way to overcome this problem [2, 3, 28]. In compositional verification, properties of...