Small group number 25 of order 32

G = D8xC4 is Direct product D8 x C_4

The Hall-Senior number of this group is 14.

G has 3 minimal generators, rank 3 and exponent 4. The centre has rank 2.

There are 2 conjugacy classes of maximal elementary abelian subgroups. Their ranks are: 3, 3.

This cohomology ring calculation is complete.

Ring structure | Completion information | Koszul information | Restriction information | Poincaré series


Ring structure

The cohomology ring has 5 generators:

There are 2 minimal relations:

This minimal generating set constitutes a Gröbner basis for the relations ideal.


Completion information

This cohomology ring was obtained from a calculation out to degree 8. The cohomology ring approximation is stable from degree 2 onwards, and Benson's tests detect stability from degree 3 onwards.

This cohomology ring has dimension 3 and depth 3. Here is a homogeneous system of parameters:

The first 3 terms h1, h2, h3 form a regular sequence of maximum length.

The first 2 terms h1, h2 form a complete Duflot regular sequence. That is, their restrictions to the greatest central elementary abelian subgroup form a regular sequence of maximal length.

Data for Benson's test:


Koszul information

A basis for R/(h1, h2, h3) is as follows.


Restriction information