Core-free 2-subnormal subgroup

Definition
A subgroup of a group is termed a core-free 2-subnormal subgroup if it is both a core-free subgroup (i.e., its defining ingredient::normal core is trivial) and a subnormal subgroup.

Weaker properties

 * Stronger than::Core-free subnormal subgroup
 * Stronger than::Core-free subgroup
 * Stronger than::2-subnormal subgroup