Several applications require reasoning over autonomously developed ontologies. Initially conceived to explicit the semantics of a certain domain, these ontologies become a powerful tool for supporting business interactions, once heterogeneities have been solved and inconsistencies eliminated. Unfortunately, a stable coherent logical state is hard to maintain in such an environment, due to normal evolution carried out independently over individual ontologies. As a result, reasoning over autonomously developed ontologies has to face with both heterogeneity and inconsistency, in order to assure correct answering. In this paper we study the problem arising in these settings. We propose an incremental reasoning approach based on a virtual reasoning space that is filled with relevant ontology entities as query answering progress. We show how to identify the set of relevant entities with respect to a user query using a set theory approach and illustrate the solution with a use case exploring the web service discovery scenario.