Every bijection yields an inverse function

Stub grade: A*

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Flesh out with some details then demote to lower grade stub. Creating page largely to jog readers' memories. Not as a reference

Statement

Let $X$ and $Y$ be sets and suppose $f:X\rightarrow Y$ is a map between them, and that it is a bijective map. Then there exists a unique function:

• $f^{-1}:Y\rightarrow X$ such that $f^{-1}(y)=x\iff f(x)=y$

Proof

Grade: E

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Easy proof.

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