Kripke Semantics - Semantics of Modal Logic

Semantics of Modal Logic

The language of propositional modal logic consists of a countably infinite set of propositional variables, a set of truth-functional connectives (in this article and ), and the modal operator ("necessarily"). The modal operator ("possibly") is the dual of and may be defined in terms of it like so: ("possibly A" is defined as equivalent to "not necessarily not A").