In this paper, we elaborate a notion of semanticWeb subsumption for processes, i.e. composed Web services. It can be used for the task of cleaning OWL-S processes libraries and to organize collections of plans into hierarchies. To that end, different types of Web services are compared. Then, we give a representation formalism and a subsumption notion for the composition of some Web services, seen as atomic actions, with preconditions and effects. A particular propositional dynamic logic is selected to formalize actions preconditions and effects. A reasoning method, for deciding processes subsumption is presented. At last, we give a customizable implementation of the reasoning method.
