Let $M$ and $N$ be $R$ modules ($R$ commutative with identity). Is it true that if fotfor every prime ideal $P$, $M_P \cong N_P$ (as $R_P$ modules) then $M \cong N$ ? Clearly the question is true if $M$ or $N$ is zero. But what about the non-zero case !?
Post Closed as "too localized" by Fernando Muro, Martin Brandenburg, Eric Wofsey, Andreas Blass, Will Sawin