Small group number 265 of order 64
G is the group 64gp265
The Hall-Senior number of this group is 104.
G has 5 minimal generators, rank 3 and exponent 4.
The centre has rank 2.
There are 5 conjugacy classes of maximal
elementary abelian subgroups. Their ranks are:
3, 3, 3, 3, 3.
This cohomology ring calculation is complete.
Ring structure
| Completion information
| Koszul information
| Restriction information
| Poincaré series
The cohomology ring has 6 generators:
- y1 in degree 1
- y2 in degree 1
- y3 in degree 1
- y4 in degree 1
- y5 in degree 1, a regular element
- r in degree 8, a regular element
There are 3 minimal relations:
- y3.y4 =
y32
+ y2.y4
+ y1.y3
+ y12
- y22.y4 =
y1.y2.y4
+ y12.y4
+ y13
- y13.y42 =
y13.y22
+ y14.y4
+ y14.y2
A minimal Gröbner basis for the relations ideal
consists of this minimal generating set, together with the
following redundant relations:
- y22.y32 =
y1.y2.y32
+ y1.y22.y3
+ y12.y32
+ y12.y2.y3
+ y12.y22
+ y14
- y13.y33 =
y13.y2.y32
+ y13.y22.y3
+ y13.y23
+ y14.y32
+ y14.y22
+ y15.y3
+ y15.y2
+ y16
- y13.y24 =
y16.y4
+ y16.y2
+ y17
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 9
onwards.
This cohomology ring has dimension 3 and depth 3.
Here is a homogeneous system of parameters:
- h1 =
y5
in degree 1
- h2 =
r
in degree 8
- h3 =
y42
+ y2.y4
+ y22
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, 8.
-
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
-
y32
in degree 2
-
y2.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
-
y2.y32
in degree 3
-
y22.y3
in degree 3
-
y23
in degree 3
-
y1.y32
in degree 3
-
y1.y2.y4
in degree 3
-
y1.y2.y3
in degree 3
-
y1.y22
in degree 3
-
y12.y4
in degree 3
-
y12.y3
in degree 3
-
y12.y2
in degree 3
-
y13
in degree 3
-
y23.y3
in degree 4
-
y1.y2.y32
in degree 4
-
y1.y22.y3
in degree 4
-
y1.y23
in degree 4
-
y12.y32
in degree 4
-
y12.y2.y4
in degree 4
-
y12.y2.y3
in degree 4
-
y12.y22
in degree 4
-
y13.y4
in degree 4
-
y13.y3
in degree 4
-
y13.y2
in degree 4
-
y14
in degree 4
-
y1.y23.y3
in degree 5
-
y12.y2.y32
in degree 5
-
y12.y22.y3
in degree 5
-
y12.y23
in degree 5
-
y13.y32
in degree 5
-
y13.y2.y3
in degree 5
-
y13.y22
in degree 5
-
y14.y4
in degree 5
-
y14.y3
in degree 5
-
y14.y2
in degree 5
-
y15
in degree 5
-
y12.y23.y3
in degree 6
-
y13.y22.y3
in degree 6
-
y14.y32
in degree 6
-
y14.y2.y3
in degree 6
-
y15.y4
in degree 6
-
y15.y3
in degree 6
-
y15.y2
in degree 6
-
y16
in degree 6
-
y15.y32
in degree 7
-
y15.y2.y3
in degree 7
-
y16.y3
in degree 7
-
y17
in degree 7
-
y17.y3
in degree 8