Small group number 233 of order 64
G is the group 64gp233
The Hall-Senior number of this group is 167.
G has 4 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
The cohomology ring has 8 generators:
- y1 in degree 1, a nilpotent element
- y2 in degree 1, a nilpotent element
- y3 in degree 1
- y4 in degree 1
- v1 in degree 4
- v2 in degree 4
- v3 in degree 4, a regular element
- v4 in degree 4, a regular element
There are 10 minimal relations:
- y42 =
y3.y4
+ y2.y3
+ y1.y4
+ y1.y2
+ y12
- y2.y4 =
y1.y4
+ y22
- y22.y3 =
y12.y3
+ y1.y22
+ y13
- y12.y4 =
0
- y4.v2 =
y3.v2
+ y2.v1
+ y1.v1
- y4.v1 =
y3.v2
+ y34.y4
+ y2.y34
+ y1.v2
+ y1.v1
+ y1.y33.y4
- y2.v2 =
y1.v2
- v22 =
y34.v2
+ y2.y33.v1
+ y1.y33.v1
+ y1.y36.y4
+ y12.y32.v1
+ y33.y4.v4
+ y33.y4.v3
+ y2.y33.v4
+ y2.y33.v3
+ y1.y32.y4.v4
+ y1.y32.y4.v3
+ y13.y2.v4
+ y13.y2.v3
+ y14.v4
+ y14.v3
- v1.v2 =
y1.y33.v2
+ y1.y36.y4
+ y12.y32.v1
+ y33.y4.v4
+ y33.y4.v3
+ y2.y33.v4
+ y1.y32.y4.v4
+ y1.y32.y4.v3
+ y1.y33.v3
+ y12.y32.v3
+ y13.y2.v4
+ y14.v4
+ y14.v3
- v12 =
y34.v2
+ y37.y4
+ y2.y37
+ y33.y4.v4
+ y34.v3
+ y2.y33.v4
+ y1.y32.y4.v4
+ y13.y2.v4
+ y14.v4
+ y14.v3
A minimal Gröbner basis for the relations ideal
consists of this minimal generating set, together with the
following redundant relations:
- y1.y2.y3 =
y12.y4
+ y23
+ y1.y22
+ y13
- y13.y3 =
0
- y24 =
y14
- y1.y23 =
y13.y2
- y12.y22 =
0
- y14.y2 =
0
- y15 =
0
- y22.v1 =
y12.v1
- y1.y2.v1 =
0
- y12.v2 =
0
- y13.v1 =
0
This cohomology ring was obtained from a calculation
out to degree 12. The cohomology ring approximation
is stable from degree 8 onwards, and
Benson's tests detect stability from degree 8
onwards.
This cohomology ring has dimension 3 and depth 2.
Here is a homogeneous system of parameters:
- h1 =
v3
in degree 4
- h2 =
v4
in degree 4
- h3 =
y32
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
-
y1.y4
in degree 2
-
y1.y3
in degree 2
-
y22
in degree 2
-
y1.y2
in degree 2
-
y12
in degree 2
-
y1.y3.y4
in degree 3
-
y12.y3
in degree 3
-
y23
in degree 3
-
y1.y22
in degree 3
-
y12.y2
in degree 3
-
y13
in degree 3
-
v2
in degree 4
-
v1
in degree 4
-
y3.v2
in degree 5
-
y3.v1
in degree 5
-
y2.v1
in degree 5
-
y1.v2
in degree 5
-
y1.v1
in degree 5
-
y2.y3.v1
in degree 6
-
y1.y3.v2
in degree 6
-
y1.y3.v1
in degree 6
-
y12.v1
in degree 6
-
y12.y3.v1
in degree 7
A basis for AnnR/(h1, h2)(h3) is as follows.
-
y23
in degree 3
-
y1.y22
in degree 3
-
y12.y2
in degree 3
-
y13
in degree 3
-
y22.h
+ y12.h
in degree 4
-
y1.y2.h
in degree 4