 The subject of combinations of logics is still a young topic in contemporary logic. Besides the pure philosophical interest offered by the possibility of defining mixed logic systems in which distinct operators obey logics of different nature, as for instance erotetic logics (the logical analysis of questions) which require combining epistemic and deontic logics, there also exist many pragmatical and methodological reasons for considering combined logics. In fact, the use of formal logic as a tool for knowledge representation in Computer Science frequently requires the integration of several logic systems into a homogeneous environment.