Abstract:
We describe the commutator invariant subgroups of a nonreduced abelian group. We find out when all commutator invariant subgroups of a separable group and an algebraically compact torsion-free group are fully invariant and describe the $E$-centers and $E$-commutants of these and some other groups.
Keywords:endomorphism ring, fully invariant subgroup, commutator of an endomorphism, $E$-center, $E$-commutant.