ThmDex – An index of mathematical definitions, results, and conjectures.
Result R4188 on D15: Set cardinality
Subresult of R4189:
Set cardinality in terms of finite ambient set
Formulation 0
Let $X$ be a D17: Finite set such that
(i) $E \subseteq X$ is a D78: Subset of $X$
Then \begin{equation} |E| = |X| - |X \setminus E| \end{equation}
Proofs
Proof 0
Let $X$ be a D17: Finite set such that
(i) $E \subseteq X$ is a D78: Subset of $X$
This result is a particular case of R4189: . $\square$