Simon King
David J. Green
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Singular
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Cohomology of group number 791 of order 128
General information on the group
- The group has 3 minimal generators and exponent 8.
- It is non-abelian.
- It has p-Rank 3.
- Its center has rank 3.
- It has a unique conjugacy class of maximal elementary abelian subgroups, which is of rank 3.
Structure of the cohomology ring
General information
- The cohomology ring is of dimension 3 and depth 3.
- The depth coincides with the Duflot bound.
- The Poincaré series is
( − 1) · (t4 + 2·t3 + t2 + 2·t + 1) |
| (t + 1)2 · (t − 1)3 · (t2 + 1) |
- The a-invariants are -∞,-∞,-∞,-3. They were obtained using the filter regular HSOP of the Benson test.
Ring generators
The cohomology ring has 12 minimal generators of maximal degree 5:
- a_1_0, a nilpotent element of degree 1
- a_1_1, a nilpotent element of degree 1
- a_1_2, a nilpotent element of degree 1
- a_2_3, a nilpotent element of degree 2
- c_2_4, a Duflot regular element of degree 2
- a_3_5, a nilpotent element of degree 3
- a_3_6, a nilpotent element of degree 3
- a_3_7, a nilpotent element of degree 3
- a_3_8, a nilpotent element of degree 3
- c_4_11, a Duflot regular element of degree 4
- c_4_12, a Duflot regular element of degree 4
- a_5_18, a nilpotent element of degree 5
Ring relations
There are 36 minimal relations of maximal degree 10:
- a_1_1·a_1_2
- a_1_0·a_1_2
- a_1_22 + a_1_12 + a_1_0·a_1_1 + a_1_02
- a_1_03
- a_1_02·a_1_1
- a_2_3·a_1_2
- a_2_32 + a_2_3·a_1_0·a_1_1 + c_2_4·a_1_02
- a_1_1·a_3_5 + c_2_4·a_1_12
- a_1_0·a_3_5 + a_2_32 + a_2_3·a_1_02 + c_2_4·a_1_0·a_1_1 + c_2_4·a_1_02
- a_1_2·a_3_6 + a_2_3·a_1_02
- a_1_1·a_3_7
- a_1_0·a_3_7 + a_2_32 + c_2_4·a_1_02
- a_1_2·a_3_7 + a_1_2·a_3_5 + a_1_1·a_3_8 + a_1_0·a_3_6 + a_2_3·a_1_02 + c_2_4·a_1_02
- a_1_2·a_3_5 + a_1_1·a_3_6 + a_1_0·a_3_8 + a_1_0·a_3_6 + a_2_32 + c_2_4·a_1_12
+ c_2_4·a_1_02
- a_1_2·a_3_8 + a_1_2·a_3_7 + a_1_2·a_3_5 + a_2_32 + c_2_4·a_1_12 + c_2_4·a_1_0·a_1_1
- a_2_3·a_3_5 + a_2_3·c_2_4·a_1_1
- a_1_02·a_3_6
- a_2_3·a_3_7
- a_3_6·a_3_7 + a_3_5·a_3_6 + c_2_4·a_1_1·a_3_6 + a_2_3·c_2_4·a_1_02
- a_3_82 + a_3_7·a_3_8 + a_3_72 + a_3_6·a_3_8 + a_3_62 + a_3_5·a_3_6 + c_2_4·a_1_0·a_3_6
+ a_2_3·c_2_4·a_1_0·a_1_1 + a_2_3·c_2_4·a_1_02 + c_2_42·a_1_12 + c_2_42·a_1_02
- a_3_7·a_3_8 + a_3_72 + a_3_5·a_3_8 + a_3_5·a_3_6 + a_3_52 + c_2_4·a_1_1·a_3_6
+ c_2_4·a_1_0·a_3_6 + a_2_3·c_2_4·a_1_0·a_1_1 + a_2_3·c_2_4·a_1_02 + c_2_42·a_1_12 + c_2_42·a_1_02
- a_3_5·a_3_6 + a_2_3·a_1_0·a_3_8 + c_2_4·a_1_1·a_3_6 + a_2_3·c_2_4·a_1_0·a_1_1
- a_3_7·a_3_8 + a_3_72 + a_3_5·a_3_7 + c_2_4·a_1_1·a_3_8 + c_2_4·a_1_1·a_3_6
+ c_2_4·a_1_0·a_3_8 + a_2_3·c_2_4·a_1_02 + c_2_42·a_1_12 + c_2_42·a_1_02
- a_3_52 + c_4_11·a_1_12 + c_4_11·a_1_0·a_1_1 + c_4_11·a_1_02 + c_2_42·a_1_0·a_1_1
+ c_2_42·a_1_02
- a_3_82 + a_3_72 + a_3_62 + c_4_12·a_1_12 + c_4_11·a_1_12 + c_4_11·a_1_0·a_1_1
+ c_2_42·a_1_12 + c_2_42·a_1_02
- a_3_82 + a_3_52 + c_4_12·a_1_0·a_1_1 + c_4_11·a_1_12 + c_2_42·a_1_12
+ c_2_42·a_1_0·a_1_1
- a_3_62 + a_3_52 + c_4_12·a_1_02 + c_4_11·a_1_0·a_1_1 + c_2_42·a_1_0·a_1_1
+ c_2_42·a_1_02
- a_3_72 + a_3_62 + a_3_52 + a_1_1·a_5_18 + a_2_3·a_1_0·a_3_6 + c_4_11·a_1_0·a_1_1
+ c_2_4·a_1_1·a_3_8 + a_2_3·c_2_4·a_1_02 + c_2_42·a_1_0·a_1_1 + c_2_42·a_1_02
- a_3_82 + a_3_7·a_3_8 + a_3_72 + a_3_62 + a_3_5·a_3_7 + a_1_0·a_5_18 + c_4_11·a_1_12
+ c_4_11·a_1_0·a_1_1 + c_2_4·a_1_1·a_3_8 + c_2_4·a_1_1·a_3_6 + a_2_3·c_2_4·a_1_0·a_1_1
- a_3_7·a_3_8 + a_1_2·a_5_18 + c_2_4·a_1_1·a_3_8 + c_2_4·a_1_0·a_3_6
+ a_2_3·c_2_4·a_1_02 + c_2_42·a_1_12 + c_2_42·a_1_0·a_1_1
- a_2_3·a_5_18 + a_2_3·a_1_02·a_3_8 + a_2_3·c_4_12·a_1_1 + a_2_3·c_4_12·a_1_0
+ a_2_3·c_2_4·a_3_8
- a_3_8·a_5_18 + c_4_12·a_1_1·a_3_6 + c_4_11·a_1_1·a_3_8 + c_4_11·a_1_1·a_3_6
+ c_4_11·a_1_0·a_3_8 + a_2_3·c_2_4·a_1_0·a_3_8 + c_2_4·c_4_12·a_1_12 + c_2_4·c_4_12·a_1_0·a_1_1 + c_2_4·c_4_12·a_1_02 + c_2_4·c_4_11·a_1_12 + c_2_4·c_4_11·a_1_0·a_1_1 + a_2_3·c_2_42·a_1_02 + c_2_43·a_1_12 + c_2_43·a_1_02
- a_3_7·a_5_18 + a_3_6·a_5_18 + c_4_12·a_1_1·a_3_8 + c_4_12·a_1_1·a_3_6
+ a_2_3·c_4_12·a_1_0·a_1_1 + a_2_3·c_4_11·a_1_0·a_1_1 + a_2_3·c_4_11·a_1_02 + c_2_4·c_4_12·a_1_0·a_1_1 + c_2_4·c_4_11·a_1_12 + c_2_4·c_4_11·a_1_0·a_1_1 + c_2_42·a_1_1·a_3_6 + c_2_42·a_1_0·a_3_6 + a_2_3·c_2_42·a_1_0·a_1_1
- a_3_5·a_5_18 + c_4_12·a_1_1·a_3_6 + c_4_12·a_1_0·a_3_8 + c_4_12·a_1_0·a_3_6
+ c_4_11·a_1_1·a_3_8 + c_4_11·a_1_1·a_3_6 + c_4_11·a_1_0·a_3_8 + a_2_3·c_4_12·a_1_02 + a_2_3·c_4_11·a_1_0·a_1_1 + a_2_3·c_4_11·a_1_02 + a_2_3·c_2_4·a_1_0·a_3_8 + a_2_3·c_2_4·a_1_0·a_3_6 + c_2_4·c_4_12·a_1_0·a_1_1 + c_2_4·c_4_11·a_1_0·a_1_1 + c_2_42·a_1_0·a_3_6 + a_2_3·c_2_42·a_1_0·a_1_1 + c_2_43·a_1_12 + c_2_43·a_1_0·a_1_1
- a_3_7·a_5_18 + c_4_12·a_1_1·a_3_8 + c_4_12·a_1_0·a_3_6 + c_2_4·a_1_2·a_5_18
+ a_2_3·c_4_12·a_1_0·a_1_1 + a_2_3·c_4_12·a_1_02 + c_2_4·c_4_12·a_1_12 + c_2_4·c_4_12·a_1_0·a_1_1 + c_2_42·a_1_1·a_3_8 + c_2_42·a_1_0·a_3_6 + a_2_3·c_2_42·a_1_02 + c_2_43·a_1_12 + c_2_43·a_1_0·a_1_1
- a_5_182 + c_4_122·a_1_0·a_1_1 + c_4_11·c_4_12·a_1_12 + c_4_11·c_4_12·a_1_0·a_1_1
+ c_4_11·c_4_12·a_1_02 + c_2_42·c_4_12·a_1_0·a_1_1 + c_2_42·c_4_11·a_1_0·a_1_1 + c_2_42·c_4_11·a_1_02 + c_2_44·a_1_12 + c_2_44·a_1_02
Data used for Benson′s test
- Benson′s completion test succeeded in degree 10.
- The completion test was perfect: It applied in the last degree in which a generator or relation was found.
- The following is a filter regular homogeneous system of parameters:
- c_2_4, a Duflot regular element of degree 2
- c_4_11, a Duflot regular element of degree 4
- c_4_12, a Duflot regular element of degree 4
- The Raw Filter Degree Type of that HSOP is [-1, -1, -1, 7].
- The filter degree type of any filter regular HSOP is [-1, -2, -3, -3].
Restriction maps
Restriction map to the greatest central el. ab. subgp., which is of rank 3
- a_1_0 → 0, an element of degree 1
- a_1_1 → 0, an element of degree 1
- a_1_2 → 0, an element of degree 1
- a_2_3 → 0, an element of degree 2
- c_2_4 → c_1_12, an element of degree 2
- a_3_5 → 0, an element of degree 3
- a_3_6 → 0, an element of degree 3
- a_3_7 → 0, an element of degree 3
- a_3_8 → 0, an element of degree 3
- c_4_11 → c_1_04, an element of degree 4
- c_4_12 → c_1_24, an element of degree 4
- a_5_18 → 0, an element of degree 5
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