Here's the problem:

Let X and Y be sets. Let f: X --> Y, and let A be a subset of Y.

Prove that f(f^{-1}(A)) is a subset of A.

Any help is much appreciated!

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- April 22nd 2012, 03:59 PMwidenerl194Need help with a subset proof
Here's the problem:

Let X and Y be sets. Let f: X --> Y, and let A be a subset of Y.

Prove that f(f^{-1}(A)) is a subset of A.

Any help is much appreciated! - April 22nd 2012, 04:47 PMPlatoRe: Need help with a subset proof
- April 22nd 2012, 05:08 PMwidenerl194Re: Need help with a subset proof
I think it might be

f(f^-1(A)) = f(x) is an element of X such that f(x) is an element of f(A).