Editing Interior algebra (section)

{{short description|Algebraic structure}}
In [[abstract algebra]], an '''interior algebra''' is a certain type of [[algebraic structure]] that encodes the idea of the topological [[Interior (topology)|interior]] of a set.  Interior algebras are to [[topology]] and the [[modal logic]] '''S4''' what [[Boolean algebra (structure)|Boolean algebra]]s are to [[set theory]] and ordinary [[propositional logic]]. Interior algebras form a [[variety (universal algebra)|variety]] of [[modal algebra]]s.