A Semantic web approach to handling soft constraints in virtual organisations

In this paper we present a proposal for representing soft constraint satisfaction problems (CSPs) within the Semantic Web architecture. The proposal is motivated by the need for a service-providing agent in a virtual organisation to reason about its commitments as soft constraints. The three essential requirements addressed are: (1) the need to have constraints express commitments in terms of Semantic Web services, (2) the need to associate utility values with constraints, to reflect the relative importance of satisfying them, and (3) the need to make statements about which constraints are satisfied and violated by a given solution. The proposal builds upon previous work in defining a Semantic Web constraint interchange format (CIF), which itself builds on the proposed Semantic Web rule language (SWRL). The paper describes an ontology for representing soft CSPs and their solutions, allowing an agent’s set of commitments to be expressed as a collection of soft constraints. The ontology is an open interchange format for soft CSPs, allowing commitment to be communicated and exchanged among the members of a virtual organisation.