Hi, everyone: I have been looking for a while without success, for the definition of equivalence for unimodular quadratic forms defined on Abelian groups . I have found instead ,t the def. of equivalence in the more common case where the two forms Q,Q' are defined on vector spaces , and the definition has to see with matrices in Sl_n(Z) . It makes sense that the equivalence of unimodular forms has to see with matrices in Sl_n(Z) , since these have determinant +/- 1 . But it is not too clear to me how we would define this equivalence if instead we had Q,Q' unimodular ,defined on Abelian groups A,A' respectively. Anyone know?. Thanks.