DAVID MAKINSON AND LEENDERT VAN DER TORRE INPUT / OUTPUT LOGICS

In a range of contexts, one comes across processes resembling inference, but where input propositions are not in ge eral included among outputs, and the operation is not in any way reversible. Exa mples arise in contexts of conditional obligations, goals, ideals, preferences , actions, and beliefs. Our purpose is to develop a theory of such input/output operations . Four are singled out: simpleminded, basic (making intelligent use of disjunctiv e nputs), simple-minded reusable (in which outputs may be recycled as inputs), and b asic reusable. They are defined semantically and characterised by derivation rules, as well as in terms of relabeling procedures and modal operators. Their behaviour is studied on both semantic and syntactic levels.