Public announcements are used in dynamic epistemic logic to model certain kinds of information change. A formula 〈ψ〉φ represents the statement that after ψ is publicly announced φ will be the case. Sometimes we want to reason about whether it is possible for φ to become true after some announcement. In order to do this an arbitrary public announcement operator ♦ can be added to an epistemic log...

The dynamic turn in Epistemic Logic is based on the idea that notions of information should be studied together with the actions that modify them. Dynamic epistemic logics have explored how knowledge and beliefs change as consequence of, among others, acts of observation and upgrade. Nevertheless, the omniscient nature of the represented agents has kept finer actions outside the picture, the mo...