Small group number 200 of order 64
G is the group 64gp200
The Hall-Senior number of this group is 108.
G has 4 minimal generators, rank 3 and exponent 4.
The centre has rank 2.
There is one conjugacy class of maximal elementary abelian
subgroups. Each maximal elementary abelian has rank 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, a nilpotent element
- y2 in degree 1, a nilpotent element
- y3 in degree 1, a nilpotent element
- y4 in degree 1
- x in degree 2, a regular element
- u in degree 5
- r in degree 8, a regular element
There are 6 minimal relations:
- y1.y4 =
y32
+ y2.y3
+ y22
+ y1.y2
- y12 =
0
- y32.y4 =
y2.y3.y4
+ y22.y4
+ y23
- y23.y42 =
y24.y4
+ y25
- y1.u =
0
- u2 =
y48.x
A minimal Gröbner basis for the relations ideal
consists of this minimal generating set, together with the
following redundant relations:
- y1.y32 =
y1.y2.y3
+ y1.y22
- y34 =
y22.y32
+ y24
- y1.y23 =
0
- y23.y32 =
y24.y3
+ y25
- y26 =
0
- y32.u =
y2.y3.u
+ y22.u
- y23.u =
0
This cohomology ring was obtained from a calculation
out to degree 12. The cohomology ring approximation
is stable from degree 10 onwards, and
Benson's tests detect stability from degree 10
onwards.
This cohomology ring has dimension 3 and depth 2.
Here is a homogeneous system of parameters:
- h1 =
x
in degree 2
- h2 =
r
in degree 8
- h3 =
y42
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, 7, 9.
-
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.y4
in degree 2
-
y32
in degree 2
-
y2.y3
in degree 2
-
y22
in degree 2
-
y1.y3
in degree 2
-
y1.y2
in degree 2
-
y2.y3.y4
in degree 3
-
y22.y4
in degree 3
-
y33
in degree 3
-
y22.y3
in degree 3
-
y23
in degree 3
-
y1.y2.y3
in degree 3
-
y1.y22
in degree 3
-
y22.y3.y4
in degree 4
-
y23.y3
in degree 4
-
y24
in degree 4
-
y1.y22.y3
in degree 4
-
u
in degree 5
-
y24.y3
in degree 5
-
y4.u
in degree 6
-
y3.u
in degree 6
-
y2.u
in degree 6
-
y3.y4.u
in degree 7
-
y2.y4.u
in degree 7
-
y2.y3.u
in degree 7
-
y22.u
in degree 7
-
y2.y3.y4.u
in degree 8
-
y22.y4.u
in degree 8
-
y22.y3.u
in degree 8
-
y22.y3.y4.u
in degree 9
A basis for AnnR/(h1, h2)(h3) is as follows.
-
y1.h
in degree 3
-
y32.h
+ y2.y3.h
+ y22.h
in degree 4
-
y1.y3.h
in degree 4
-
y1.y2.h
in degree 4
-
y33.h
+ y2.y32.h
+ y22.y3.h
in degree 5
-
y23.h
in degree 5
-
y1.y2.y3.h
in degree 5
-
y1.y22.h
in degree 5
-
y23.y3.h
in degree 6
-
y24.h
in degree 6
-
y1.y22.y3.h
in degree 6
-
y24.y3.h
in degree 7