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Preimage


The preimage of a point y under a function f:X->Y is the set f^(-1)(y)={x in X:f(x)=y}, consisting of all x whose image is y. The image of x is f(x). Images are elements of the range, while preimages are subsets (possibly the empty set) of the domain.


Portions of this entry contributed by Todd Rowland

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Cite this as:

Weisstein, Eric W., with contributions by Todd Rowland. "Preimage." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Preimage.html

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