## Stably free and the Eilenberg swindle

I already mentioned the idea of stably isomorphic for a ring $R$: two $R$-modules $A$ and $B$ are stably isomorphic if there exists a natural number $n$ such that $A\oplus R^n\cong B\oplus R^n$. Let's examine a specific case: if $A$ is stably isomorphic to a free module, then let's call it stably free. So, to […]