Abstract
One of the important application of service composition techniques lies in the field of business process management. Essentially a business process can be considered as a composition of services, which is usually prepared by domain experts, and many tasks still have to be performed manually. These include the design and creation of the process itself or the modification of an existing one when business requirements change. Any form of automation and support we can bring to the tasks of maintenance and evolution are highly beneficial. One way of creating a new business process is by the combination of two existing ones which naturally should retain the behavioral features of both original processes. In this paper, we introduce a formal language to express behavioral properties of processes together with its semantics, and we show how it supports process merging.