# Math Help - Fibers

1. ## Fibers

7. $f: A \rightarrow B$ is a surjective map of sets. We want to prove that $a \sim b$ if and only if $f(a) = f(b)$ is an equivalence relation whose equivalence classes are fibers of $f$.

2. Here it is: $
\begin{array}{l}
\left( {\forall x \in A} \right)\left[ {f(x) = f(x)} \right] \\