Extended Models: An Alternative Semantics for Action Model Logic

Timo Eckhardt (University of Melbourne)

Timo Eckhardt (Melbourne) will present "Extended Models: An Alternative Semantics for Action Model Logic" at 11 in Old Quad G10.

Abstract: In recent years many different logics of communication have been discussed. One of the most promising approaches has been that of Action Model Logic, where possible actions are represented in action frames and are combined with an epistemic model representing the situation before the action took place. Making an epistemic action like an announcement is then changing the model from the old to the combined model. I discuss a different aproach to its semantic, extended model semantics, in which instead of using model change, we represent epistemic actions as a special type of model operation that combines the underlying model with the new model via a new type of modal arrow.

The standard axiomatisation of AML is wholly reductive to the underlying Epistemic Logic. Given the new semantics it is possible to give a new set of axioms that is not fully reductive. Lastly, I want to discuss why this is new approach is useful both looking at the axioms and extensions of AML.