▾ Set of symbols
▾ Alphabet
▾ Deduction system
▾ Theory
▾ Zermelo-Fraenkel set theory
▾ Set
▾ Binary cartesian set product
▾ Binary relation
▾ Map
Idempotent map
Formulation 0
A D18: Map $f : X \to Y$ is idempotent if and only if \begin{equation} \forall \, x \in X : f(f(x)) = f(x) \end{equation}
Results
» R3896: Idempotence of real expectation