Small group number 234 of order 64
G is the group 64gp234
The Hall-Senior number of this group is 164.
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 8 generators:
- y1 in degree 1
- y2 in degree 1
- y3 in degree 1
- y4 in degree 1
- w1 in degree 3
- w2 in degree 3
- v1 in degree 4, a regular element
- v2 in degree 4, a regular element
There are 10 minimal relations:
- y32 =
y1.y4
+ y1.y3
+ y12
- y2.y4 =
y12
- y1.y42 =
y13
- y12.y4 =
y12.y2
- y4.w2 =
y4.w1
+ y1.w2
- y2.w2 =
y1.w2
+ y1.w1
- y1.y4.w1 =
y12.w1
- w22 =
y12.y3.w2
+ y14.y2.y3
+ y15.y3
+ y16
+ y42.v1
+ y12.v2
- w1.w2 =
y1.y22.w1
+ y12.y3.w1
+ y13.w1
+ y15.y2
+ y16
+ y42.v1
+ y1.y4.v1
+ y1.y2.v2
+ y12.v2
- w12 =
y23.w1
+ y1.y2.y3.w1
+ y1.y22.w1
+ y12.y3.w1
+ y42.v1
+ y22.v2
+ y12.v2
+ y12.v1
A minimal Gröbner basis for the relations ideal
consists of this minimal generating set, together with the
following redundant relations:
- y12.y22 =
y14
- y12.y2.w1 =
y13.w1
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 3.
Here is a homogeneous system of parameters:
- h1 =
v1
in degree 4
- h2 =
v2
in degree 4
- h3 =
y42
+ y22
+ y1.y4
in degree 2
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:
-
Raw filter degree type:
-1, -1, -1, 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
-
w2
in degree 3
-
w1
in degree 3
-
y22.y3
in degree 3
-
y1.y3.y4
in degree 3
-
y1.y2.y3
in degree 3
-
y12.y3
in degree 3
-
y12.y2
in degree 3
-
y13
in degree 3
-
y4.w1
in degree 4
-
y3.w2
in degree 4
-
y3.w1
in degree 4
-
y2.w1
in degree 4
-
y1.w2
in degree 4
-
y1.w1
in degree 4
-
y12.y2.y3
in degree 4
-
y13.y3
in degree 4
-
y3.y4.w1
in degree 5
-
y2.y3.w1
in degree 5
-
y1.y3.w2
in degree 5
-
y1.y3.w1
in degree 5
-
y1.y2.w1
in degree 5
-
y12.w2
in degree 5
-
y12.w1
in degree 5
-
y1.y2.y3.w1
in degree 6
-
y12.y3.w2
in degree 6
-
y12.y3.w1
in degree 6
-
y13.w1
in degree 6
-
y13.y3.w1
in degree 7