Cohomology of group number 525 of order 128

About the group Ring generators Ring relations Completion information Restriction maps Back to groups 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 2.
  • It has 3 conjugacy classes of maximal elementary abelian subgroups, which are all of rank 3.

Structure of the cohomology ring

General information

  • The cohomology ring is of dimension 3 and depth 3.
  • The depth exceeds the Duflot bound, which is 2.
  • The Poincaré series is
    ( − 1) · (t2  +  1)2
    (t  −  1)3 · (t4  +  1)
  • The a-invariants are -∞,-∞,-∞,-3. They were obtained using the filter regular HSOP of the Benson test.

About the group Ring generators Ring relations Completion information Restriction maps Back to groups of order 128

Ring generators

The cohomology ring has 12 minimal generators of maximal degree 8:

  1. a_1_0, a nilpotent element of degree 1
  2. b_1_1, an element of degree 1
  3. b_1_2, an element of degree 1
  4. a_2_2, a nilpotent element of degree 2
  5. b_2_3, an element of degree 2
  6. b_2_4, an element of degree 2
  7. b_2_7, an element of degree 2
  8. c_2_6, a Duflot regular element of degree 2
  9. a_3_6, a nilpotent element of degree 3
  10. a_3_14, a nilpotent element of degree 3
  11. a_5_35, a nilpotent element of degree 5
  12. c_8_88, a Duflot regular element of degree 8

About the group Ring generators Ring relations Completion information Restriction maps Back to groups of order 128

Ring relations

There are 36 minimal relations of maximal degree 10:

  1. a_1_02
  2. a_1_0·b_1_1
  3. a_1_0·b_1_2
  4. a_2_2·a_1_0
  5. b_2_3·a_1_0
  6. b_2_4·a_1_0
  7. b_2_4·b_1_1 + b_2_3·b_1_2
  8. b_1_23 + b_1_1·b_1_22 + b_2_7·b_1_1
  9. b_2_32 + c_2_6·b_1_12
  10. b_2_3·b_2_4 + c_2_6·b_1_1·b_1_2
  11. b_2_42 + c_2_6·b_1_22
  12. b_2_7·b_1_1·b_1_2 + b_2_7·b_1_12 + a_2_2·b_1_22 + a_2_2·b_1_1·b_1_2 + a_2_22
  13. b_2_7·b_1_22 + b_2_7·b_1_1·b_1_2 + b_1_2·a_3_6 + a_2_2·b_2_4
  14. a_1_0·a_3_6
  15. b_1_1·a_3_6 + a_2_2·b_1_22 + a_2_2·b_1_1·b_1_2 + a_2_2·b_2_3 + a_2_22
  16. b_1_2·a_3_14 + a_2_2·b_1_22 + a_2_2·b_2_7 + a_2_2·b_2_4
  17. b_2_4·b_1_22 + b_2_3·b_1_22 + b_2_3·b_2_7 + a_1_0·a_3_14
  18. b_1_1·a_3_14 + a_2_2·b_1_22 + a_2_2·b_2_3
  19. b_1_22·a_3_6 + a_2_2·b_2_7·b_1_1 + a_2_2·b_2_4·b_1_2 + a_2_22·b_1_2
  20. b_2_3·b_2_7·b_1_2 + b_2_3·b_2_7·b_1_1 + b_2_3·a_3_6 + a_2_2·c_2_6·b_1_1
  21. b_2_4·b_2_7·b_1_2 + b_2_3·b_2_7·b_1_2 + b_2_4·a_3_6 + a_2_2·c_2_6·b_1_2
  22. b_2_3·b_2_7·b_1_2 + b_2_3·b_2_7·b_1_1 + a_2_2·b_2_7·b_1_2 + a_2_2·b_2_7·b_1_1
       + a_2_2·b_2_4·b_1_2 + a_2_2·b_2_3·b_1_2 + a_2_2·a_3_6
  23. b_2_3·a_3_14 + a_2_2·b_2_4·b_1_2 + a_2_2·c_2_6·b_1_1
  24. b_2_72·b_1_2 + b_2_7·a_3_6 + b_2_4·a_3_14 + a_2_2·b_2_7·b_1_1 + a_2_2·b_2_4·b_1_2
       + a_2_22·b_1_2 + a_2_2·c_2_6·b_1_2
  25. b_2_3·b_2_7·b_1_2 + b_2_3·b_2_7·b_1_1 + a_2_2·b_2_7·b_1_2 + a_2_2·b_2_7·b_1_1
       + a_2_2·b_2_4·b_1_2 + a_2_2·b_2_3·b_1_2 + a_2_2·a_3_14 + a_2_22·b_1_2
  26. b_2_7·b_1_2·a_3_6 + a_2_2·b_2_4·b_2_7 + a_3_62 + a_2_22·c_2_6
  27. b_2_4·b_1_2·a_3_6 + a_2_2·b_2_72 + a_2_2·b_2_3·b_2_7 + a_3_6·a_3_14
       + a_2_2·c_2_6·b_1_22 + a_2_22·c_2_6
  28. b_2_7·b_1_2·a_3_6 + b_2_4·b_1_2·a_3_6 + a_2_2·b_2_72 + a_2_2·b_2_4·b_2_7
       + a_2_2·b_2_3·b_2_7 + a_3_142 + b_2_7·a_1_0·a_3_14 + a_2_22·b_1_22 + a_2_22·b_2_7
       + a_2_22·b_2_4 + a_2_2·c_2_6·b_1_22 + a_2_22·c_2_6
  29. b_1_2·a_5_35 + b_2_7·b_1_2·a_3_6 + a_2_2·b_2_7·b_1_12 + a_2_2·b_2_3·b_1_22
       + a_2_2·b_2_3·b_1_1·b_1_2 + a_2_2·b_2_3·b_2_7 + a_2_22·b_1_1·b_1_2
       + b_2_7·c_2_6·b_1_12 + c_2_6·b_1_2·a_3_6 + a_2_2·c_2_6·b_1_1·b_1_2
       + a_2_2·b_2_4·c_2_6 + a_2_22·c_2_6
  30. b_2_4·b_1_2·a_3_6 + a_2_2·b_2_3·b_2_7 + a_1_0·a_5_35 + a_2_22·b_2_4
       + a_2_2·c_2_6·b_1_22
  31. b_1_1·a_5_35 + a_2_2·b_1_12·b_1_22 + a_2_2·b_1_13·b_1_2 + a_2_2·b_2_3·b_1_22
       + a_2_2·b_2_3·b_1_12 + a_2_2·b_2_3·b_2_7 + a_2_22·b_1_22 + a_2_22·b_1_1·b_1_2
       + a_2_22·b_1_12 + a_2_22·b_2_7 + b_2_7·c_2_6·b_1_12 + a_2_2·c_2_6·b_1_22
       + a_2_22·c_2_6
  32. b_2_3·a_5_35 + a_2_2·b_2_3·b_1_1·b_1_22 + a_2_2·b_2_3·b_1_12·b_1_2
       + a_2_2·b_2_4·a_3_6 + a_2_22·b_2_4·b_1_2 + a_2_22·b_2_3·b_1_2 + a_2_22·b_2_3·b_1_1
       + b_2_3·b_2_7·c_2_6·b_1_1 + a_2_2·c_2_6·b_1_1·b_1_22 + a_2_2·c_2_6·b_1_13
       + a_2_2·b_2_7·c_2_6·b_1_2 + a_2_2·b_2_4·c_2_6·b_1_2 + a_2_2·c_2_6·a_3_6
       + a_2_22·c_2_6·b_1_2
  33. b_2_4·a_5_35 + b_2_4·b_2_7·a_3_6 + a_2_2·b_2_3·b_2_7·b_1_1 + a_2_22·b_2_3·b_1_2
       + b_2_3·b_2_7·c_2_6·b_1_1 + b_2_4·c_2_6·a_3_6 + a_2_2·c_2_6·b_1_1·b_1_22
       + a_2_2·c_2_6·b_1_12·b_1_2 + a_2_2·b_2_7·c_2_6·b_1_2 + a_2_2·b_2_3·c_2_6·b_1_2
       + a_2_2·c_2_6·a_3_6 + a_2_2·c_2_62·b_1_2
  34. a_2_2·a_5_35 + a_2_2·b_2_7·a_3_6 + a_2_22·b_1_1·b_1_22 + a_2_22·b_1_12·b_1_2
       + a_2_22·b_2_4·b_1_2 + a_2_22·b_2_3·b_1_1 + a_2_2·b_2_7·c_2_6·b_1_2
       + a_2_22·c_2_6·b_1_2
  35. a_3_6·a_5_35 + b_2_7·a_3_62 + a_2_22·b_2_3·b_2_7 + a_2_2·b_2_4·b_2_7·c_2_6
       + c_2_6·a_3_62 + a_2_22·c_2_6·b_1_22 + a_2_22·c_2_6·b_1_12
       + a_2_22·b_2_7·c_2_6 + a_2_22·b_2_4·c_2_6 + a_2_22·c_2_62
  36. a_5_352 + b_2_72·a_3_62 + a_2_22·c_2_6·b_1_12·b_1_22 + a_2_22·c_2_6·b_1_14
       + a_2_2·b_2_7·c_2_62·b_1_12 + c_2_62·a_3_62 + a_2_22·c_2_62·b_1_22
       + a_2_22·c_2_62·b_1_1·b_1_2 + a_2_22·c_2_63

About the group Ring generators Ring relations Completion information Restriction maps Back to groups of order 128

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:
    1. c_2_6, a Duflot regular element of degree 2
    2. c_8_88, a Duflot regular element of degree 8
    3. b_1_12 + b_2_7, an element of degree 2
  • The Raw Filter Degree Type of that HSOP is [-1, -1, -1, 9].
  • The filter degree type of any filter regular HSOP is [-1, -2, -3, -3].

About the group Ring generators Ring relations Completion information Restriction maps Back to groups of order 128

Restriction maps

Restriction map to the greatest central el. ab. subgp., which is of rank 2

  1. a_1_0 → 0, an element of degree 1
  2. b_1_1 → 0, an element of degree 1
  3. b_1_2 → 0, an element of degree 1
  4. a_2_2 → 0, an element of degree 2
  5. b_2_3 → 0, an element of degree 2
  6. b_2_4 → 0, an element of degree 2
  7. b_2_7 → 0, an element of degree 2
  8. c_2_6 → c_1_02, an element of degree 2
  9. a_3_6 → 0, an element of degree 3
  10. a_3_14 → 0, an element of degree 3
  11. a_5_35 → 0, an element of degree 5
  12. c_8_88 → c_1_18, an element of degree 8

Restriction map to a maximal el. ab. subgp. of rank 3

  1. a_1_0 → 0, an element of degree 1
  2. b_1_1 → c_1_2, an element of degree 1
  3. b_1_2 → 0, an element of degree 1
  4. a_2_2 → 0, an element of degree 2
  5. b_2_3 → c_1_0·c_1_2, an element of degree 2
  6. b_2_4 → 0, an element of degree 2
  7. b_2_7 → 0, an element of degree 2
  8. c_2_6 → c_1_02, an element of degree 2
  9. a_3_6 → 0, an element of degree 3
  10. a_3_14 → 0, an element of degree 3
  11. a_5_35 → 0, an element of degree 5
  12. c_8_88 → c_1_14·c_1_24 + c_1_18, an element of degree 8

Restriction map to a maximal el. ab. subgp. of rank 3

  1. a_1_0 → 0, an element of degree 1
  2. b_1_1 → 0, an element of degree 1
  3. b_1_2 → 0, an element of degree 1
  4. a_2_2 → 0, an element of degree 2
  5. b_2_3 → 0, an element of degree 2
  6. b_2_4 → 0, an element of degree 2
  7. b_2_7 → c_1_22, an element of degree 2
  8. c_2_6 → c_1_02, an element of degree 2
  9. a_3_6 → 0, an element of degree 3
  10. a_3_14 → 0, an element of degree 3
  11. a_5_35 → 0, an element of degree 5
  12. c_8_88 → c_1_14·c_1_24 + c_1_18 + c_1_04·c_1_24, an element of degree 8

Restriction map to a maximal el. ab. subgp. of rank 3

  1. a_1_0 → 0, an element of degree 1
  2. b_1_1 → c_1_2, an element of degree 1
  3. b_1_2 → c_1_2, an element of degree 1
  4. a_2_2 → 0, an element of degree 2
  5. b_2_3 → c_1_0·c_1_2, an element of degree 2
  6. b_2_4 → c_1_0·c_1_2, an element of degree 2
  7. b_2_7 → 0, an element of degree 2
  8. c_2_6 → c_1_02, an element of degree 2
  9. a_3_6 → 0, an element of degree 3
  10. a_3_14 → 0, an element of degree 3
  11. a_5_35 → 0, an element of degree 5
  12. c_8_88 → c_1_28 + c_1_14·c_1_24 + c_1_18 + c_1_02·c_1_26 + c_1_04·c_1_24
       + c_1_06·c_1_22, an element of degree 8

About the group Ring generators Ring relations Completion information Restriction maps Back to groups of order 128


Simon A. King David J. Green
Fakultät für Mathematik und Informatik Fakultät für Mathematik und Informatik
Friedrich-Schiller-Universität Jena Friedrich-Schiller-Universität Jena
Ernst-Abbe-Platz 2 Ernst-Abbe-Platz 2
D-07743 Jena D-07743 Jena
Germany Germany
E-mail: simon dot king at uni hyphen jena dot de
Tel: +49 (0)3641 9-46184
Fax: +49 (0)3641 9-46162
Office: Zi. 3524, Ernst-Abbe-Platz 2
E-mail: david dot green at uni hyphen jena dot de
Tel: +49 3641 9-46166
Fax: +49 3641 9-46162
Office: Zi 3512, Ernst-Abbe-Platz 2

Last change: 25.08.2009