This paper reports on a fertile marriage between madAgents, a Java and Prolog based multi-agent platform, and EVOLP, a logic programming based language to represent and reason about evolving knowledge. The resulting system, presented with a formal semantic characterisation and implemented using a combination of Java, XSB Prolog and Smodels, provides an improvement of madAgents, allowing for the implementation of a richer agent architecture where agents' beliefs and behavior, as well as their

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... lution, are specifiable in EVOLP. It inherits the merits of Answer Set Programming (e.g., default negation for reasoning about incomplete knowledge, a semantics based on multiple answer-sets for reasoning about several possible worlds, etc.) on top of which we add all the specific merits of EVOLP for specifying evolving knowledge. At he same time, the resulting system provides a proof of principle that EVOLP can easily be adopted by existing MAS, to represent an evolving belief base, or also to represent the agent's evolving behavior.