Possible Duplicate:
When can a pair of groups be embedded in each other?
Let $G,H$ be two groups. Let $f:G\rightarrow H$, $g:H\rightarrow G$ be injective group homomorphisms. From the Schroeder-Bernstein Theorem, it follows that the underlying sets of $G,H$ are equipotent. Does it follow that $G,H$ are isomorphic ?
Thanks in Advance.