Extensions of Groups

Whenever a group G has a normal subgroup N, we may say that G is an extension   of  N   by some group H which is isomorphic to the quotient G/N.   This page aims to describe the four ways in which an extension can work. It uses non-standard terminology.

The four ways are:

Whichever method we use, the size of G is the product of the sizes of N and H.

Here are some examples of all these four types of group extension

See also my main index page for groups.

Copyright N.S.Wedd 2008