Retraction-invariant normal subgroup

Definition
A subgroup of a group is termed a retraction-invariant normal subgroup if it is both a normal subgroup and a retraction-invariant subgroup.

Stronger properties

 * Weaker than::Fully invariant subgroup
 * Weaker than::Retraction-invariant direct factor
 * Weaker than::Retraction-invariant central factor
 * Weaker than::Retraction-invariant characteristic subgroup

Weaker properties

 * Stronger than::Normal subgroup
 * Stronger than::Retraction-invariant subgroup