In order to obtain semantic interoperability in open MultiAgent Systems, agents need to agree on the basis of different ontologies. In this paper we formally define mapping as correspondences between queries over ontologies. Individual mappings are computed by specialized agents using different mapping approaches. Next, these agents use argumentation to exchange their local results, in order to agree on the mappings. Based on their preferences and strength of the arguments, the agents compute their preferred mapping sets. The arguments in such preferred sets are viewed as the set of globally acceptable arguments. These arguments are then represented as conjunctive queries in OWL-DL extended with DL-safe rules [9], a restriction imposed to attain decidability in such query answering system.