Failure Semantics for Modal Transition Systems

With the aim to preserve deadlock freedom, we define a new refinement relation for modal transition systems (MTS), using an MTS-specific variant of testing in the sense of De Nicola and Hennessy. We characterize this refinement with a kind of failure semantics, and we show that it 'supports itself' e.g. in the sense of thoroughness - in contrast to the standard modal refinement. We present a conjunction operator w.r.t. our new refinement, this operator is very different from others found in the literature, and it demonstrates that the conjunction of two MTSs is an MTS - again in contrast to the case of modal refinement. Finally, we also consider a may-testing approach.