Towards a hybrid logic of acquaintance and awarness

A (partial) solution to the well-known problem of "logical omniscience" in modal-like logics for knowledge and belief is suggested: it is based on the notion of "awareness of a proposition" and on that of "explicit belief", viewed as "classical" belief modulo awareness. Our formal treatment relies on the idea that an agent is aware of a proposition ? iff he is "capable of attributing a meaning to ?": this idea has lead us to develop a logic for belief where the fact that an agent is aware of a proposition may be characterized in terms of the "terminological content" of the proposition. Following the introduction of the awareness requirement, our notion of explicit belief does not suffer from logical omniscience: in particular, it is not closed with respect to logical equivalence and "valid implication". We argue that this is a useful feature when such logics are applied to e.g. dialogue modelling and, in general, to the specification of intelligent rational agents.