Show that any finitely generated torsion free module is a free module..

Any help is appreciated ..

Printable View

- Jan 18th 2011, 04:36 AMmath.djModules over P.I.D
Show that any finitely generated torsion free module is a free module..

Any help is appreciated .. - Jan 18th 2011, 05:28 AMTheArtofSymmetry
See Hungerford's algebra book p221.

The sketch of the proof is

Let A be a finitely generated torsion-free module over PID R. Let X be a finite set of nonzero generators of A. Let S be a maximal subset of X such that the submodule F generated by the inclusion is free. For each , there exists such that . Let . It follows that . Since A is torsion-free, given by is a R-module homomorphism whose kernel is trivial. So, . Verify that rA is a submodule of A and a submodule of a free R-module for PID R is free. Thus, A is free.