The aim of this work is the design of a framework for the revision of knowledge in abductive reasoning agents, based on interaction. We address issues such as: how to exploit knowledge multiplicity to find solutions to problems that agents could not individually solve, what information must be passed or requested, how can agents take advantage from the answers that they obtain, and how can they revise their reasoning process as a consequence of interacting with each other. In this preliminary report, we describe a novel negotiation framework in which agents will exchange not only abductive hypotheses but also metaknowledge, such as their own integrity constraints. Besides, we formalise some aspects of such a framework, by introducing an algebra of integrity constraints, aimed at formally supporting the updating/revising process of the agent knowledge. 1 Multiple-source knowledge and coordinated reasoning The agent metaphor has recently become a very popular way to model distributed sys...