Malnormal subgroup
In mathematics, in the field of group theory, a subgroup of a group is termed malnormal if for any in but not in, and intersect only in the identity element.
Some facts about malnormality:
- An intersection of malnormal subgroups is malnormal.
- Malnormality is transitive, that is, a malnormal subgroup of a malnormal subgroup is malnormal.
- The trivial subgroup and the whole group are malnormal subgroups. A normal subgroup that is also malnormal must be one of these.
- Every malnormal subgroup is a special type of C-group called a trivial intersection subgroup or TI subgroup.
element of H, is a normal subgroup of G, called the "Frobenius kernel", and G is the semidirect product of H and N.