Formal Models of Awareness

This special issue on Formal Models of Awareness contains five papers that concentrate on different approaches to the notion of awareness. They include syntactic and semantic approaches to modelling awareness (awareness of formulas as opposed to awareness of semantic objects such as sets of possoble worlds) and an alternative view from the multi-agent systems perspective where awareness is identified as the ability to perceive and understand actions of other agents. Velázquez-Quesada studies a logic of plausibility acknowledgement models used to interpret the notions of implicit and explicit beliefs. The models use the notion of a formula being acknowledged as true that is similar to syntactic awareness in that the set of formulas acknowledged as true by an agent is not assumed to be closed under logical consequence. However it has a different meaning (of not just being aware of the formula, but being aware that the formula is is true). A dynamic epistemic logic over such models is considered, and it is shown how to model belief revision and inferences performed by agents. The paper by Soler-Toscano and Velázquez-Quesada belongs to the same tradition of considering explicit information or awareness of non-omniscient reasoners. It focusses on the problem of abductive reasoning for agents whose information is not closed under consequence and who may not have complete reasoning abilities. It generalises the abductive problem for non-omnisient reasoners as finding a hypothesis which, under the agent’s inferential abilities and explicit information, would entail a given observation. Furthermore, it formalises abductive reasoning by non-omniscient