Polynomial-time isomorphism testing of groups of most finite orders

Abstract

[PLEASE SEE COMMENT] We consider the isomorphism problem for finite abelian groups and finite meta-cyclic groups. We prove that for a dense set of positive integers $n$, isomorphism testing for abelian groups of black-box type of order $n$ can be done in time polynomial in $\log n$. We also prove that for a dense set of orders $n$ with given prime factors, one can test isomorphism for coprime meta-cyclic groups of black-box type of order $n$ in time polynomial in $\log n$. Prior methods for these two classes of groups have running times exponential in $\log n$.