If the factor of a finitely generated module is free then submodule is also finitely generated

211 Views Asked by At

All rings are commutative, associative and with 1.

Consider short exact sequence $0 \rightarrow M' \rightarrow M \rightarrow M'' \rightarrow 0$ of $R$-modules. How to show that if $M$ is finitely generated and $M''$ is free then $M'$ is also finitely generated?

1

There are 1 best solutions below

0
On BEST ANSWER

If $M''$ is free then the sequence is split, so $M'$ is a direct summand of $M$. In particular, $M'$ is isomorphic to a factor module of $M$ and thus it is finitely generated.