Prove that free modules are projective

1k Views Asked by At

Prove that free modules are projective.

Help me.

1

There are 1 best solutions below

4
On BEST ANSWER

Definition: $M$ is projective iff for every surjective morphism $f:A\rightarrow B$, and every morphism $g:M\rightarrow B$ there is morphism $h:M\rightarrow A$ such that $fh=g$.

Now if $M$ is free with base $\{x_i\}$ then we can define $g$ setting $x_i\mapsto a_i\in f^{-1}(g(x_i))$.