maximal subgroup
Let G be a group.
A subgroup H of G
is said to be a maximal subgroup of G
if H≠G and there is no subgroup K of G
such that H<K<G.
Note that a maximal subgroup of G is not maximal (http://planetmath.org/MaximalElement) among all subgroups of G,
but only among all proper subgroups
of G.
For this reason, maximal subgroups are sometimes called maximal proper subgroups.
Similarly, a normal subgroup N of G
is said to be a maximal normal subgroup
(or maximal proper normal subgroup) of G
if N≠G and there is no normal subgroup K of G
such that N<K<G.
We have the following theorem:
Theorem.
A normal subgroup N of a group G is a maximal normal subgroup if and only if the quotient (http://planetmath.org/QuotientGroup) G/N is simple (http://planetmath.org/Simple).
Title | maximal subgroup |
Canonical name | MaximalSubgroup |
Date of creation | 2013-03-22 12:23:46 |
Last modified on | 2013-03-22 12:23:46 |
Owner | yark (2760) |
Last modified by | yark (2760) |
Numerical id | 15 |
Author | yark (2760) |
Entry type | Definition |
Classification | msc 20E28 |
Synonym | maximal proper subgroup |
Related topic | MaximalElement |
Defines | maximal |
Defines | maximal normal subgroup |
Defines | maximal proper normal subgroup |
Defines | simplicity of quotient group |