Small group number 3 of order 125
G = E125 is Extraspecial 5-group of order 125 and exponent 5
G has 2 minimal generators, rank 2 and exponent 5.
The centre has rank 1.
There are 6 conjugacy classes of maximal
elementary abelian subgroups. Their ranks are:
2, 2, 2, 2, 2, 2.
This cohomology ring calculation is complete.
Ring structure
| Completion information
| Koszul information
| Restriction information
| Poincaré series
The cohomology ring has 12 generators:
- y1 in degree 1, a nilpotent element
- y2 in degree 1, a nilpotent element
- x1 in degree 2, a nilpotent element
- x2 in degree 2, a nilpotent element
- x3 in degree 2
- x4 in degree 2
- w1 in degree 3, a nilpotent element
- w2 in degree 3, a nilpotent element
- s in degree 7, a nilpotent element
- r in degree 8
- q in degree 9, a nilpotent element
- p in degree 10, a regular element
There are 50 minimal relations:
- y22 =
0
- y1.y2 =
0
- y12 =
0
- y2.x4 =
y1.x3
- y2.x2 =
0
- y2.x1 =
y1.x2
- y1.x1 =
0
- x2.x4 =
y2.w1
- 2y1.w2
- x2.x3 =
- y2.w2
- x1.x4 =
y1.w1
- x1.x3 =
2y2.w1
- y1.w2
- x22 =
0
- x1.x2 =
0
- x12 =
0
- x4.w2 =
x3.w1
- 2y1.x3.x4
- 2y1.x32
- x2.w2 =
0
- x2.w1 =
x1.w2
- x1.w1 =
0
- w22 =
0
- w12 =
0
- y2.s =
y1.x3.x4.w1
- y1.x32.w2
+ 2y1.x32.w1
- y1.s =
y1.x42.w1
+ 2y1.x3.x4.w1
- y1.x32.w1
- x4.s =
x43.w1
+ 2x3.x42.w1
- x32.x4.w1
+ 2y1.x32.x42
+ 2y1.x33.x4
+ 2y1.x34
- x3.s =
x3.x42.w1
+ 2x32.x4.w1
- x33.w1
+ 2y1.x3.x43
+ 2y1.x33.x4
+ 2y1.x34
- y2.r =
y1.x3.x43
- 2y1.x32.x42
- y1.x34
- y1.r =
- 2y1.x3.x43
- y1.x33.x4
+ y1.x34
- x2.s =
0
- x1.s =
0
- x4.r =
- 2x3.x44
- x33.x42
+ x34.x4
+ 2y1.x33.w2
+ y1.x33.w1
- x3.r =
x3.x44
- 2x32.x43
- x34.x4
+ 2y2.x33.w2
+ y1.x33.w2
- x2.r =
- y1.x3.x42.w1
+ 2y1.x32.x4.w1
+ y1.x33.w2
- x1.r =
- 2y1.x3.x42.w1
+ y1.x33.w2
- y1.x33.w1
- w2.s =
y1.x3.x42.w1
- y1.x32.x4.w1
+ y1.x33.w1
- w1.s =
- 2y1.x32.x4.w1
- 2y1.x33.w2
- 2y1.x33.w1
- y2.q =
- 2y2.x33.w2
- 2y1.x3.x42.w1
- 2y1.x32.x4.w1
- y1.x33.w2
+ 2y1.x33.w1
- y1.q =
2y1.x43.w1
- 2y1.x3.x42.w1
+ 2y1.x32.x4.w1
- y1.x33.w2
- y1.x33.w1
- w2.r =
x3.x43.w1
- 2x32.x42.w1
- x34.w1
+ 2y1.x32.x43
- y1.x33.x42
+ 2y1.x34.x4
- w1.r =
- 2x3.x43.w1
- x33.x4.w1
+ x34.w1
- x4.q =
2x44.w1
- 2x3.x43.w1
+ 2x32.x42.w1
- x33.x4.w1
- x34.w1
- y1.x32.x43
- 2y1.x33.x42
+ 2y1.x34.x4
+ y1.x35
- x3.q =
- 2x3.x43.w1
- 2x32.x42.w1
+ 2x33.x4.w1
- 2x34.w2
- x34.w1
+ 2y1.x32.x43
- y1.x33.x42
- 2y1.x34.x4
- 2y1.x35
- x2.q =
0
- x1.q =
0
- w2.q =
y1.x32.x42.w1
+ y1.x33.x4.w1
- 2y1.x34.w2
- w1.q =
y1.x32.x42.w1
+ 2y1.x33.x4.w1
- y1.x34.w2
- 2y1.x34.w1
- s2 =
0
- s.r =
x33.x43.w1
- x34.x42.w1
+ x35.x4.w1
- 2y1.x34.x43
- y1.x35.x42
+ y1.x37
- r2 =
x35.x43
- 2x37.x4
+ 2y1.x35.x4.w1
- 2y1.x36.w2
- 2y1.x36.w1
- s.q =
- 2y1.x34.x42.w1
+ y1.x35.x4.w1
+ y1.x36.w2
- r.q =
- x35.x42.w1
+ 2x36.x4.w1
- x37.w1
- 2y1.x35.x43
- y1.x36.x42
- 2y1.x37.x4
- q2 =
0
A minimal Gröbner basis for the relations ideal
consists of this minimal generating set, together with the
following redundant relations:
- y2.x3.w1 =
y1.x3.w2
- y2.w1.w2 =
0
- y1.w1.w2 =
0
- x3.w1.w2 =
2y1.x32.w2
+ 2y1.x32.w1
- y1.x3.x44 =
y1.x35
- x3.x45 =
x35.x4
- y1.x3.x43.w1 =
y1.x34.w2
- x3.x44.w1 =
x35.w1
This cohomology ring was obtained from a calculation
out to degree 18. The cohomology ring approximation
is stable from degree 18 onwards, and
Benson's tests detect stability from degree 18
onwards.
This cohomology ring has dimension 2 and depth 1.
Here is a homogeneous system of parameters:
- h1 =
p
in degree 10
- h2 =
x42
- x3.x4
+ x32
in degree 4
The first
term h1 forms
a regular sequence of maximum length.
The first
term h1 forms
a complete Duflot regular sequence.
That is, its restriction to the greatest central elementary abelian
subgroup forms a regular sequence of maximal length.
Data for Benson's test:
-
Raw filter degree type:
-1, 6, 12.
-
Filter degree type:
-1, -2, -2.
-
α = 0
-
The system of parameters is very strongly quasi-regular.
-
The regularity conjecture is satisfied.
A basis for R/(h1, h2) is as follows.
-
1
in degree 0
-
y2
in degree 1
-
y1
in degree 1
-
x4
in degree 2
-
x3
in degree 2
-
x2
in degree 2
-
x1
in degree 2
-
w2
in degree 3
-
w1
in degree 3
-
y2.x3
in degree 3
-
y1.x4
in degree 3
-
y1.x3
in degree 3
-
y1.x2
in degree 3
-
x3.x4
in degree 4
-
x32
in degree 4
-
y2.w2
in degree 4
-
y2.w1
in degree 4
-
y1.w2
in degree 4
-
y1.w1
in degree 4
-
x4.w1
in degree 5
-
x3.w2
in degree 5
-
x3.w1
in degree 5
-
y1.x3.x4
in degree 5
-
y1.x32
in degree 5
-
x1.w2
in degree 5
-
x32.x4
in degree 6
-
x33
in degree 6
-
w1.w2
in degree 6
-
y1.x3.w2
in degree 6
-
y1.x3.w1
in degree 6
-
s
in degree 7
-
x32.w2
in degree 7
-
x32.w1
in degree 7
-
y1.x32.x4
in degree 7
-
y1.x33
in degree 7
-
r
in degree 8
-
x33.x4
in degree 8
-
x34
in degree 8
-
y1.x32.w2
in degree 8
-
y1.x32.w1
in degree 8
-
q
in degree 9
-
x33.w2
in degree 9
-
x33.w1
in degree 9
-
y1.x33.x4
in degree 9
-
y1.x34
in degree 9
-
x34.x4
in degree 10
-
x35
in degree 10
-
y1.x33.w2
in degree 10
-
y1.x33.w1
in degree 10
-
x34.w2
in degree 11
-
x34.w1
in degree 11
-
y1.x34.w1
in degree 12
A basis for AnnR/(h1)(h2) is as follows.
-
y1.x2
in degree 3
-
y2.w1
- y1.w2
in degree 4
-
x1.w2
in degree 5
-
w1.w2
- 2y1.x3.w2
- 2y1.x3.w1
in degree 6