Finite p-groups which are non-inner nilpotent

Abstract

A group G is called a non-inner nilpotent group, whenever it is nilpotent with respect to a non-inner automorphism. In 2018, all finitely generated abelian non-inner nilpotent groups have been classified. Actually, the authors proved that a finitely generated abelian group G is a non-inner nilpotent group, if G is not isomorphic to cyclic groups Z_p_1p_2...p_t and Z, for a positive integer t and distinct primes p_1, p_2,..., p_t. We conjecture that all finite non-abelian p-groups are non-inner nilpotent and we prove this conjecture for finite $p$-groups of nilpotency class 2 or of co-class 2.