Difference between revisions of "Bijection"

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Revision as of 17:43, 12 February 2015

A bijection is a 1:1 map. A map which is both injective and surjective.

It has the useful property that for

$$f:X\rightarrow Y$$ that $$f^{-1}(y)$$ is always defined, and is at most one element.

Thus

$$f^{-1}$$ behaves as a normal function (rather than the always-valid but less useful $$f^{-1}:Y\rightarrow\mathcal{P}(X)$$ where $$\mathcal{P}(X)$$ denotes the power set of $$X$$ )