A procedure for mediating between service requesters and providers

In MAS, middle agents are commonly used to find appropriate provider agents for a given request. Most middle agents match the request with providers´ advertised capabilities, selecting a set of providers which are all able to treat it. We describe a mediation procedure to complement matchmaking. Given a request, the selected providers send monetary bids to the middle agent, expressing their will to get it. The middle agent maintains a social evaluation of their performing quality. Selection of the expected n providers is obtained through a balance between bids and estimated qualities. Two main cases are treated in the proposed general framework: competition and requisition. In a competition case, when more than n providers want to treat the request, the procedure generalizes a Vickrey auction. Requisition occurs when at least one provider does not want to treat the request and less than n want to. The procedure then generalizes a fair imposition mechanism: the requisition cost is supported by all the providers with similar capabilities. In both cases, the estimated quality of the providers influences the selection process and the definition of the amount of payment owed by the providers.