Small group number 236 of order 64
G is the group 64gp236
The Hall-Senior number of this group is 166.
G has 4 minimal generators, rank 3 and exponent 4.
The centre has rank 2.
There are 4 conjugacy classes of maximal
elementary abelian subgroups. Their ranks are:
3, 3, 3, 3.
This cohomology ring calculation is complete.
Ring structure
| Completion information
| Koszul information
| Restriction information
| Poincaré series
The cohomology ring has 7 generators:
- y1 in degree 1
 
- y2 in degree 1
 
- y3 in degree 1
 
- y4 in degree 1
 
- w in degree 3
 
- v1 in degree 4, a regular element
 
- v2 in degree 4, a regular element
 
There are 6 minimal relations:
- y32 =
y22
+ y1.y4
+ y1.y3
 
- y2.y4 =
y12
 
- y1.y42 =
y1.y22
 
- y12.y4 =
y12.y2
 
- y1.y4.w =
y1.y2.w
 
- w2 =
y23.w
+ y12.y2.w
+ y15.y3
+ y15.y2
+ y16
+ y42.v1
+ y22.v1
+ y12.v2
 
A minimal Gröbner basis for the relations ideal
consists of this minimal generating set, together with the
following redundant relations:
- y1.y23 =
y13.y2
 
- y12.y22 =
y14
 
- y1.y22.w =
y13.w
 
This cohomology ring was obtained from a calculation
out to degree 12. The cohomology ring approximation
is stable from degree 6 onwards, and
Benson's tests detect stability from degree 7
onwards.
This cohomology ring has dimension 3 and depth 2.
Here is a homogeneous system of parameters:
- h1 =
v1
in degree 4
 
- h2 =
v2
in degree 4
 
- h3 =
y42
+ y3.y4
+ y2.y3
in degree 2
 
The first
2 terms h1, h2 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:
- 
Raw filter degree type:
-1, -1, 4, 7.
 - 
Filter degree type:
-1, -2, -3, -3.
 - 
α = 0
 - 
The system of parameters is very strongly quasi-regular.
 - 
The regularity conjecture is satisfied.
 
A basis for R/(h1, h2, h3) is as follows.
- 
1
in degree 0
 
- 
y4
in degree 1
 
- 
y3
in degree 1
 
- 
y2
in degree 1
 
- 
y1
in degree 1
 
- 
y3.y4
in degree 2
 
- 
y2.y3
in degree 2
 
- 
y22
in degree 2
 
- 
y1.y4
in degree 2
 
- 
y1.y3
in degree 2
 
- 
y1.y2
in degree 2
 
- 
y12
in degree 2
 
- 
w
in degree 3
 
- 
y23
in degree 3
 
- 
y1.y2.y3
in degree 3
 
- 
y1.y22
in degree 3
 
- 
y12.y3
in degree 3
 
- 
y12.y2
in degree 3
 
- 
y13
in degree 3
 
- 
y4.w
in degree 4
 
- 
y3.w
in degree 4
 
- 
y2.w
in degree 4
 
- 
y1.w
in degree 4
 
- 
y12.y2.y3
in degree 4
 
- 
y13.y2
in degree 4
 
- 
y3.y4.w
in degree 5
 
- 
y2.y3.w
in degree 5
 
- 
y22.w
in degree 5
 
- 
y1.y3.w
in degree 5
 
- 
y1.y2.w
in degree 5
 
- 
y12.w
in degree 5
 
- 
y23.w
in degree 6
 
- 
y1.y2.y3.w
in degree 6
 
- 
y12.y3.w
in degree 6
 
- 
y12.y2.w
in degree 6
 
- 
y12.y2.y3.w
in degree 7
 
A basis for AnnR/(h1, h2)(h3) is as follows.
- 
y1.y4
+ y1.y2
in degree 2
 
- 
y1.y22
+ y1.h
in degree 3
 
- 
y13
+ y1.h
in degree 3
 
- 
y13.y2
+ y1.y2.h
in degree 4