ThmDex – An index of mathematical definitions, results, and conjectures.

Result R125 on D78: Subset

Subset relation is reflexive

Formulation 0

Let $X$ be a D11: Set.

Then \begin{equation} X \subseteq X \end{equation}

Formulation 2

Let $X$ be a D11: Set such that

(i)	$\mathcal{P}(X)$ is the D80: Power set of $X$

Then \begin{equation} X \in \mathcal{P}(X) \end{equation}