Simon King
David J. Green
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Singular
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Cohomology of group number 16 of order 243
General information on the group
- The group has 2 minimal generators and exponent 27.
- It is non-abelian.
- It has p-Rank 3.
- Its center has rank 1.
- 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 1.
- The depth coincides with the Duflot bound.
- The Poincaré series is
( − 1) · (t4 − t3 + t2 − t + 1) |
| (t − 1)3 · (t2 − t + 1) · (t2 + t + 1) |
- The a-invariants are -∞,-3,-3,-3. They were obtained using the filter regular HSOP of the Benson test.
Ring generators
The cohomology ring has 17 minimal generators of maximal degree 8:
- a_1_0, a nilpotent element of degree 1
- a_1_1, a nilpotent element of degree 1
- a_2_0, a nilpotent element of degree 2
- a_2_1, a nilpotent element of degree 2
- b_2_2, an element of degree 2
- a_3_2, a nilpotent element of degree 3
- a_3_3, a nilpotent element of degree 3
- a_4_3, a nilpotent element of degree 4
- b_4_4, an element of degree 4
- a_5_5, a nilpotent element of degree 5
- a_5_6, a nilpotent element of degree 5
- a_6_7, a nilpotent element of degree 6
- b_6_8, an element of degree 6
- c_6_9, a Duflot regular element of degree 6
- a_7_11, a nilpotent element of degree 7
- a_7_12, a nilpotent element of degree 7
- a_8_14, a nilpotent element of degree 8
Ring relations
There are 8 "obvious" relations:
a_1_02, a_1_12, a_3_22, a_3_32, a_5_52, a_5_62, a_7_112, a_7_122
Apart from that, there are 95 minimal relations of maximal degree 16:
- a_1_0·a_1_1
- a_2_0·a_1_0
- a_2_1·a_1_1 + a_2_0·a_1_1
- a_2_1·a_1_0 − a_2_0·a_1_1
- b_2_2·a_1_0
- a_2_02
- a_2_0·a_2_1
- a_2_12
- a_2_0·b_2_2
- − a_2_1·b_2_2 + a_1_1·a_3_2
- a_1_0·a_3_2
- a_1_0·a_3_3
- a_2_0·a_3_2
- a_2_1·a_3_2
- a_2_0·a_3_3
- a_4_3·a_1_1 − a_2_1·a_3_3
- a_4_3·a_1_0
- b_4_4·a_1_0
- b_2_2·a_4_3 − a_3_2·a_3_3 − b_2_2·a_1_1·a_3_3
- a_2_0·a_4_3
- a_2_1·a_4_3
- a_2_0·b_4_4
- − a_2_1·b_4_4 + a_1_1·a_5_5 − b_2_2·a_1_1·a_3_3
- a_1_0·a_5_5
- a_1_0·a_5_6
- a_4_3·a_3_3
- a_4_3·a_3_2 + a_1_1·a_3_2·a_3_3
- a_2_0·a_5_5
- a_2_1·a_5_5 − a_1_1·a_3_2·a_3_3
- − b_4_4·a_3_3 − b_4_4·a_3_2 + b_2_2·a_5_6 − b_2_22·a_3_2 − a_1_1·a_3_2·a_3_3
- a_2_0·a_5_6
- a_6_7·a_1_1 − a_2_1·a_5_6
- a_6_7·a_1_0
- b_6_8·a_1_1 + b_4_4·a_3_2 − b_2_2·a_5_5 + b_2_22·a_3_3 − a_2_1·a_5_6 + a_1_1·a_3_2·a_3_3
- b_6_8·a_1_0
- a_4_32
- a_3_3·a_5_6 + a_3_2·a_5_6 + b_2_2·a_3_2·a_3_3
- − a_4_3·b_4_4 − a_3_3·a_5_6 − b_2_2·a_3_2·a_3_3 + b_2_2·a_1_1·a_5_6 − b_2_2·a_1_1·a_5_5
+ b_2_22·a_1_1·a_3_3 − b_2_22·a_1_1·a_3_2
- b_2_2·a_6_7 + a_3_3·a_5_5 + a_3_2·a_5_5 − b_2_2·a_3_2·a_3_3
- a_2_0·a_6_7
- a_2_1·a_6_7
- a_2_0·b_6_8
- a_2_1·b_6_8 + a_3_2·a_5_5 − b_2_2·a_3_2·a_3_3
- a_3_2·a_5_5 + a_1_1·a_7_11 − b_2_2·a_3_2·a_3_3
- a_1_0·a_7_11
- − a_3_3·a_5_6 + a_3_3·a_5_5 + a_1_1·a_7_12 − b_2_2·a_3_2·a_3_3
- a_1_0·a_7_12
- a_4_3·a_5_6 + a_1_1·a_3_2·a_5_6 + b_2_2·a_1_1·a_3_2·a_3_3
- a_6_7·a_3_3 + a_4_3·a_5_6 − a_4_3·a_5_5 + b_2_2·a_1_1·a_3_2·a_3_3
- a_6_7·a_3_2 − a_4_3·a_5_6 + a_4_3·a_5_5 − b_2_2·a_1_1·a_3_2·a_3_3
- − b_6_8·a_3_2 + b_4_42·a_1_1 + b_2_2·a_7_11 + b_2_2·b_4_4·a_3_2 − b_2_22·a_5_5
+ b_2_22·b_4_4·a_1_1 + b_2_23·a_3_3 − a_4_3·a_5_5
- a_2_0·a_7_11
- a_2_1·a_7_11
- − b_6_8·a_3_3 − b_4_42·a_1_1 + b_2_2·a_7_12 − b_2_2·b_4_4·a_3_2 + b_2_22·a_5_5
− b_2_22·b_4_4·a_1_1 − b_2_23·a_3_3 + a_4_3·a_5_6 + a_4_3·a_5_5 + b_2_2·a_1_1·a_3_2·a_3_3
- a_2_0·a_7_12
- a_4_3·a_5_6 − a_4_3·a_5_5 + a_2_1·a_7_12 + b_2_2·a_1_1·a_3_2·a_3_3
- a_8_14·a_1_1 + a_4_3·a_5_6 − a_4_3·a_5_5 + b_2_2·a_1_1·a_3_2·a_3_3
- a_8_14·a_1_0
- a_4_3·a_6_7
- a_4_3·b_6_8 + a_3_3·a_7_11 − b_4_4·a_1_1·a_5_6 + b_4_4·a_1_1·a_5_5 + b_2_22·a_1_1·a_5_6
− b_2_23·a_1_1·a_3_2
- − b_4_4·a_6_7 + a_5_5·a_5_6 + a_3_2·a_7_11 − b_4_4·a_1_1·a_5_5 + b_2_2·a_3_2·a_5_6
+ b_2_22·a_3_2·a_3_3 + b_2_22·a_1_1·a_5_6 + b_2_22·a_1_1·a_5_5 − b_2_23·a_1_1·a_3_3 − b_2_23·a_1_1·a_3_2
- b_4_4·a_6_7 − a_5_5·a_5_6 − b_2_2·a_3_2·a_5_6 + b_2_2·a_1_1·a_7_11 − b_2_22·a_3_2·a_3_3
- b_4_4·a_6_7 − a_4_3·b_6_8 − a_5_5·a_5_6 + a_3_3·a_7_12 + a_3_2·a_7_12 + b_4_4·a_1_1·a_5_6
− b_2_2·a_3_2·a_5_6 − b_2_22·a_3_2·a_3_3 + b_2_22·a_1_1·a_5_6 − b_2_22·a_1_1·a_5_5 + b_2_23·a_1_1·a_3_3 − b_2_23·a_1_1·a_3_2
- − a_3_3·a_7_12 − b_4_4·a_1_1·a_5_6 + b_4_4·a_1_1·a_5_5 + b_2_2·a_1_1·a_7_12
+ b_2_22·a_1_1·a_5_6 − b_2_23·a_1_1·a_3_2
- − a_4_3·b_6_8 + b_2_2·a_8_14 − a_3_3·a_7_12 + b_4_4·a_1_1·a_5_5 − b_2_22·a_1_1·a_5_5
− b_2_23·a_1_1·a_3_3 − b_2_23·a_1_1·a_3_2
- a_2_0·a_8_14
- a_2_1·a_8_14
- a_6_7·a_5_6 + a_6_7·a_5_5
- a_4_3·a_7_11 + a_1_1·a_5_5·a_5_6 − b_2_2·a_1_1·a_3_2·a_5_6 + b_2_22·a_1_1·a_3_2·a_3_3
- a_6_7·a_5_5 + a_4_3·a_7_12 − a_1_1·a_5_5·a_5_6 + b_2_2·a_1_1·a_3_2·a_5_6
− b_2_22·a_1_1·a_3_2·a_3_3
- − a_6_7·a_5_5 + a_1_1·a_3_2·a_7_12
- − b_6_8·a_5_5 + b_4_4·a_7_11 + b_4_42·a_3_2 − b_2_2·b_4_4·a_5_5 + b_2_2·b_4_42·a_1_1
+ b_2_22·a_7_12 + b_2_23·a_5_6 − b_2_23·a_5_5 + b_2_23·b_4_4·a_1_1 + b_2_24·a_3_3 − b_2_24·a_3_2 − a_6_7·a_5_5 + a_1_1·a_5_5·a_5_6 − b_2_2·a_1_1·a_3_2·a_5_6 + b_2_22·a_1_1·a_3_2·a_3_3 − b_2_22·c_6_9·a_1_1
- − b_6_8·a_5_6 + b_4_4·a_7_12 + b_4_4·a_7_11 + b_2_2·b_4_42·a_1_1 + b_2_22·a_7_11
+ b_2_22·b_4_4·a_3_2 − b_2_23·a_5_5 + b_2_23·b_4_4·a_1_1 + b_2_24·a_3_3 − a_1_1·a_5_5·a_5_6 − b_2_22·a_1_1·a_3_2·a_3_3
- a_8_14·a_3_3 + a_1_1·a_5_5·a_5_6
- a_8_14·a_3_2 − a_6_7·a_5_5 − a_1_1·a_5_5·a_5_6 + b_2_22·a_1_1·a_3_2·a_3_3
- a_6_72
- − b_6_82 − b_4_43 + b_2_22·b_4_42 + b_2_23·b_6_8 − b_2_24·b_4_4 − a_6_7·b_6_8
+ a_5_6·a_7_11 + a_5_5·a_7_12 − b_4_4·a_1_1·a_7_11 − b_2_2·b_4_4·a_1_1·a_5_6 − b_2_22·a_3_2·a_5_6 − b_2_22·a_1_1·a_7_11 − b_2_23·a_3_2·a_3_3 − b_2_23·c_6_9 + b_2_2·c_6_9·a_1_1·a_3_3
- b_6_82 + b_4_43 − b_2_22·b_4_42 − b_2_23·b_6_8 + b_2_24·b_4_4 + a_5_6·a_7_12
+ a_5_5·a_7_11 + b_4_4·a_1_1·a_7_11 + b_2_2·b_4_4·a_1_1·a_5_6 + b_2_22·a_3_2·a_5_6 + b_2_22·a_1_1·a_7_11 + b_2_23·a_3_2·a_3_3 + b_2_23·c_6_9 − b_2_2·c_6_9·a_1_1·a_3_3
- b_6_82 + b_4_43 − b_2_22·b_4_42 − b_2_23·b_6_8 + b_2_24·b_4_4 − a_5_6·a_7_11
+ a_5_5·a_7_11 + b_4_4·a_1_1·a_7_11 + b_2_2·a_3_2·a_7_12 + b_2_2·b_4_4·a_1_1·a_5_6 + b_2_2·b_4_4·a_1_1·a_5_5 + b_2_22·a_3_2·a_5_6 + b_2_23·a_3_2·a_3_3 − b_2_23·a_1_1·a_5_6 − b_2_23·a_1_1·a_5_5 + b_2_24·a_1_1·a_3_3 + b_2_24·a_1_1·a_3_2 + b_2_23·c_6_9 − b_2_2·c_6_9·a_1_1·a_3_3
- − b_6_82 − b_4_43 + b_2_22·b_4_42 + b_2_23·b_6_8 − b_2_24·b_4_4 + a_5_6·a_7_11
+ b_2_2·b_4_4·a_1_1·a_5_6 − b_2_2·b_4_4·a_1_1·a_5_5 − b_2_22·a_3_2·a_5_6 + b_2_22·a_1_1·a_7_12 + b_2_22·a_1_1·a_7_11 − b_2_23·a_3_2·a_3_3 − b_2_23·a_1_1·a_5_5 + b_2_24·a_1_1·a_3_3 − b_2_23·c_6_9 + b_2_2·c_6_9·a_1_1·a_3_3 + b_2_2·c_6_9·a_1_1·a_3_2
- − b_6_82 − b_4_43 + b_2_22·b_4_42 + b_2_23·b_6_8 − b_2_24·b_4_4 + a_6_7·b_6_8
− a_5_6·a_7_11 + b_4_4·a_1_1·a_7_12 + b_4_4·a_1_1·a_7_11 − b_2_2·b_4_4·a_1_1·a_5_6 + b_2_2·b_4_4·a_1_1·a_5_5 − b_2_22·a_3_2·a_5_6 + b_2_22·a_1_1·a_7_11 − b_2_23·a_3_2·a_3_3 − b_2_23·a_1_1·a_5_6 − b_2_23·a_1_1·a_5_5 + b_2_24·a_1_1·a_3_3 + b_2_24·a_1_1·a_3_2 − b_2_23·c_6_9 − b_2_2·c_6_9·a_1_1·a_3_3 − b_2_2·c_6_9·a_1_1·a_3_2
- a_4_3·a_8_14
- − b_6_82 − b_4_43 + b_2_22·b_4_42 + b_2_23·b_6_8 − b_2_24·b_4_4 + a_6_7·b_6_8
+ b_4_4·a_8_14 − b_4_4·a_1_1·a_7_11 − b_2_22·a_3_2·a_5_6 − b_2_22·a_1_1·a_7_11 − b_2_23·a_3_2·a_3_3 + b_2_23·a_1_1·a_5_6 − b_2_24·a_1_1·a_3_2 − b_2_23·c_6_9 − b_2_2·c_6_9·a_1_1·a_3_3 − b_2_2·c_6_9·a_1_1·a_3_2
- − b_6_8·a_7_11 − b_4_42·a_5_5 − b_4_43·a_1_1 + b_2_2·b_4_42·a_3_2
+ b_2_22·b_4_4·a_5_6 − b_2_22·b_4_4·a_5_5 − b_2_22·b_4_42·a_1_1 + b_2_23·a_7_11 + b_2_24·a_5_6 − b_2_25·a_3_2 + a_6_7·a_7_11 + b_2_2·a_1_1·a_5_5·a_5_6 + b_2_2·a_1_1·a_3_2·a_7_12 + b_2_22·a_1_1·a_3_2·a_5_6 + b_2_23·a_1_1·a_3_2·a_3_3 − b_2_22·c_6_9·a_3_2 − b_2_23·c_6_9·a_1_1
- − b_6_8·a_7_12 − b_6_8·a_7_11 − b_4_42·a_5_6 + b_2_2·b_4_42·a_3_2 + b_2_22·b_4_4·a_5_6
+ b_2_23·a_7_12 + b_2_23·a_7_11 − b_2_23·b_4_4·a_3_2 − b_2_24·a_5_6 + b_2_25·a_3_2 + a_6_7·a_7_11 − b_2_22·a_1_1·a_3_2·a_5_6 + b_2_23·a_1_1·a_3_2·a_3_3 − b_2_22·c_6_9·a_3_3 − b_2_22·c_6_9·a_3_2 − c_6_9·a_1_1·a_3_2·a_3_3
- − b_6_8·a_7_11 − b_4_42·a_5_5 − b_4_43·a_1_1 + b_2_2·b_4_42·a_3_2
+ b_2_22·b_4_4·a_5_6 − b_2_22·b_4_4·a_5_5 − b_2_22·b_4_42·a_1_1 + b_2_23·a_7_11 + b_2_24·a_5_6 − b_2_25·a_3_2 + a_1_1·a_5_5·a_7_12 − b_2_2·a_1_1·a_5_5·a_5_6 − b_2_23·a_1_1·a_3_2·a_3_3 − b_2_22·c_6_9·a_3_2 − b_2_23·c_6_9·a_1_1 + c_6_9·a_1_1·a_3_2·a_3_3
- a_6_7·a_7_12 + a_6_7·a_7_11
- b_6_8·a_7_11 + b_4_42·a_5_5 + b_4_43·a_1_1 − b_2_2·b_4_42·a_3_2 − b_2_22·b_4_4·a_5_6
+ b_2_22·b_4_4·a_5_5 + b_2_22·b_4_42·a_1_1 − b_2_23·a_7_11 − b_2_24·a_5_6 + b_2_25·a_3_2 + a_8_14·a_5_5 + a_6_7·a_7_11 + b_2_2·a_1_1·a_5_5·a_5_6 + b_2_22·a_1_1·a_3_2·a_5_6 + b_2_22·c_6_9·a_3_2 + b_2_23·c_6_9·a_1_1 − c_6_9·a_1_1·a_3_2·a_3_3
- b_6_8·a_7_11 + b_4_42·a_5_5 + b_4_43·a_1_1 − b_2_2·b_4_42·a_3_2 − b_2_22·b_4_4·a_5_6
+ b_2_22·b_4_4·a_5_5 + b_2_22·b_4_42·a_1_1 − b_2_23·a_7_11 − b_2_24·a_5_6 + b_2_25·a_3_2 + a_8_14·a_5_6 + a_6_7·a_7_11 − b_2_2·a_1_1·a_5_5·a_5_6 − b_2_22·a_1_1·a_3_2·a_5_6 + b_2_23·a_1_1·a_3_2·a_3_3 + b_2_22·c_6_9·a_3_2 + b_2_23·c_6_9·a_1_1 + c_6_9·a_1_1·a_3_2·a_3_3
- a_7_11·a_7_12 + b_4_4·a_5_5·a_5_6 + b_4_42·a_1_1·a_5_6 + b_2_2·b_4_4·a_1_1·a_7_12
− b_2_22·a_3_2·a_7_12 − b_2_22·b_4_4·a_1_1·a_5_6 + b_2_22·b_4_4·a_1_1·a_5_5 − b_2_23·a_3_2·a_5_6 − b_2_23·a_1_1·a_7_12 + b_2_24·a_1_1·a_5_5 − b_2_25·a_1_1·a_3_3 + b_2_2·c_6_9·a_3_2·a_3_3 + b_2_22·c_6_9·a_1_1·a_3_3 + b_2_22·c_6_9·a_1_1·a_3_2
- b_6_8·a_8_14 + a_7_11·a_7_12 − b_4_4·a_5_5·a_5_6 + b_4_42·a_1_1·a_5_5
+ b_2_2·b_4_4·a_1_1·a_7_11 + b_2_22·a_3_2·a_7_12 − b_2_22·b_4_4·a_1_1·a_5_6 + b_2_22·b_4_4·a_1_1·a_5_5 + b_2_23·a_3_2·a_5_6 + b_2_23·a_1_1·a_7_12 − b_2_24·a_1_1·a_5_6 + b_2_24·a_1_1·a_5_5 − b_2_25·a_1_1·a_3_3 + b_2_25·a_1_1·a_3_2 − b_2_2·c_6_9·a_3_2·a_3_3 + b_2_22·c_6_9·a_1_1·a_3_2
- a_6_7·a_8_14
- a_8_14·a_7_12 − b_4_4·a_1_1·a_5_5·a_5_6 + b_2_2·a_1_1·a_5_5·a_7_12
+ b_2_23·a_1_1·a_3_2·a_5_6 − b_2_2·c_6_9·a_1_1·a_3_2·a_3_3
- a_8_14·a_7_11 − b_4_4·a_1_1·a_5_5·a_5_6 − b_2_2·a_1_1·a_5_5·a_7_12
+ b_2_23·a_1_1·a_3_2·a_5_6 − b_2_2·c_6_9·a_1_1·a_3_2·a_3_3
- a_8_142
Data used for Benson′s test
- Benson′s completion test succeeded in degree 16.
- 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_6_9, a Duflot regular element of degree 6
- b_4_43 − b_2_22·b_4_42 − b_2_23·b_6_8 + b_2_24·b_4_4 − b_2_26 + b_2_23·c_6_9, an element of degree 12
- b_2_2, an element of degree 2
- The Raw Filter Degree Type of that HSOP is [-1, 3, 15, 17].
- The filter degree type of any filter regular HSOP is [-1, -2, -3, -3].
- We found that there exists some filter regular HSOP formed by the first term of the above HSOP, together with 2 elements of degree 4.
Restriction maps
Restriction map to the greatest central el. ab. subgp., which is of rank 1
- a_1_0 → 0, an element of degree 1
- a_1_1 → 0, an element of degree 1
- a_2_0 → 0, an element of degree 2
- a_2_1 → 0, an element of degree 2
- b_2_2 → 0, an element of degree 2
- a_3_2 → 0, an element of degree 3
- a_3_3 → 0, an element of degree 3
- a_4_3 → 0, an element of degree 4
- b_4_4 → 0, an element of degree 4
- a_5_5 → 0, an element of degree 5
- a_5_6 → 0, an element of degree 5
- a_6_7 → 0, an element of degree 6
- b_6_8 → 0, an element of degree 6
- c_6_9 → c_2_03, an element of degree 6
- a_7_11 → 0, an element of degree 7
- a_7_12 → 0, an element of degree 7
- a_8_14 → 0, an element of degree 8
Restriction map to a maximal el. ab. subgp. of rank 3
- a_1_0 → 0, an element of degree 1
- a_1_1 → a_1_1, an element of degree 1
- a_2_0 → 0, an element of degree 2
- a_2_1 → − a_1_1·a_1_2, an element of degree 2
- b_2_2 → c_2_4, an element of degree 2
- a_3_2 → c_2_5·a_1_1 − c_2_4·a_1_2, an element of degree 3
- a_3_3 → − c_2_5·a_1_1 + c_2_4·a_1_2, an element of degree 3
- a_4_3 → c_2_4·a_1_1·a_1_2, an element of degree 4
- b_4_4 → c_2_4·a_1_1·a_1_2 − c_2_52 + c_2_4·c_2_5 − c_2_3·c_2_4, an element of degree 4
- a_5_5 → c_2_52·a_1_2 + c_2_52·a_1_1 − c_2_4·c_2_5·a_1_2 + c_2_4·c_2_5·a_1_1 + c_2_42·a_1_2
− c_2_3·c_2_5·a_1_1 + c_2_3·c_2_4·a_1_2, an element of degree 5
- a_5_6 → c_2_4·c_2_5·a_1_1 − c_2_42·a_1_2, an element of degree 5
- a_6_7 → 0, an element of degree 6
- b_6_8 → − c_2_42·a_1_1·a_1_2 + c_2_53 − c_2_42·c_2_5, an element of degree 6
- c_6_9 → c_2_42·a_1_1·a_1_2 + c_2_53 + c_2_4·c_2_52 + c_2_42·c_2_5 − c_2_3·c_2_52
+ c_2_3·c_2_4·c_2_5 + c_2_3·c_2_42 + c_2_32·c_2_4 + c_2_33, an element of degree 6
- a_7_11 → − c_2_53·a_1_2 − c_2_4·c_2_52·a_1_1 + c_2_42·c_2_5·a_1_2 + c_2_42·c_2_5·a_1_1
+ c_2_3·c_2_52·a_1_1 − c_2_3·c_2_4·c_2_5·a_1_1 + c_2_3·c_2_42·a_1_1 − c_2_32·c_2_4·a_1_1, an element of degree 7
- a_7_12 → c_2_53·a_1_2 + c_2_4·c_2_52·a_1_1 − c_2_42·c_2_5·a_1_2 − c_2_42·c_2_5·a_1_1
− c_2_3·c_2_52·a_1_1 + c_2_3·c_2_4·c_2_5·a_1_1 − c_2_3·c_2_42·a_1_1 + c_2_32·c_2_4·a_1_1, an element of degree 7
- a_8_14 → − c_2_53·a_1_1·a_1_2 + c_2_42·c_2_5·a_1_1·a_1_2 + c_2_43·a_1_1·a_1_2, an element of degree 8
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