Let $G$ be a semigroup and let $S$ be a subset of $G$. The normalizer of $S$ is \(C_G(S) = \{g\in G\mid gS=Sg\}.\) When $G$ is a group, this may be written equivalently as \(C_G(S) = \{g\in G\mid gSg^{-1}\}.\)
Wikidata ID: Q1761121