Miscellaneous Classification Results for 2-Designs

This is the webpage of the paper ``Miscellaneous Classification Results for 2-Designs'' by P. Kaski and P. R. J. Östergård (Discrete Mathematics 280 (2004), 65-75).

The designs, resolvable designs, and their resolutions with a nontrivial automorphism group are available through the links on the table entries. See below for a description of the file format.

The resolvable 2-(16,4,2) designs

|Aut(D)|Resolvable designs
1314 263
29 588
388
4661
53
694
8158
107
1237
1673
182
2422
3232
362
489
645
721
965
1202
1281
1922
2561
3842
7681
11521
19201
57601
Total325 062

All the 10799 resolvable designs with a nontrivial automorphism group [res1642.txt.gz, gzip-compressed 1.4MB].

The 2-(13,6,5) designs

|Aut(D)|Designs
119 063 352
27 619
31 651
4113
653
1210
131
392
1561
Total19 072 802

All the 9450 designs with a nontrivial automorphism group [d1365.txt.gz, gzip-compressed 0.4MB].

The 2-(14,7,6) designs

|Aut(D)|Designs
115 097 318
210 934
32 514
4143
698
125
132
394
781
Total15 111 019

All the 13701 designs with a nontrivial automorphism group [d1476.txt.gz, gzip-compressed 0.6MB].


File format

The design data files are in ASCII format suitable for the GAP toolkit.

Resolvable designs

Below is an example resolvable design listed together with its resolutions.
# Design 10799: 1 resolution(s), autom. group order 5760, decomposable
D[10799]:=[[1,2,3,4],[1,2,3,4],[1,5,6,7],[1,5,6,7],
           [1,8,9,10],[1,8,9,10],[1,11,12,13],[1,11,12,13],
           [1,14,15,16],[1,14,15,16],[2,5,8,11],[2,5,8,11],
           [2,6,12,14],[2,6,12,14],[2,7,9,15],[2,7,9,15],
           [2,10,13,16],[2,10,13,16],[3,5,13,15],[3,5,13,15],
           [3,6,8,16],[3,6,8,16],[3,7,10,12],[3,7,10,12],
           [3,9,11,14],[3,9,11,14],[4,5,10,14],[4,5,10,14],
           [4,6,9,13],[4,6,9,13],[4,7,11,16],[4,7,11,16],
           [4,8,12,15],[4,8,12,15],[5,9,12,16],[5,9,12,16],
           [6,10,11,15],[6,10,11,15],[7,8,13,14],[7,8,13,14]];
G[10799]:=Group([(5,6,7)(8,12,15)(9,11,14)(10,13,16),
                 (5,8,11)(6,9,13)(7,10,12)(14,15,16),
                 (3,4)(6,7)(8,11)(9,12)(10,13)(14,15),
                 (2,3)(6,7)(8,15)(9,16)(10,14)(11,13),
                 (2,5)(3,6)(4,7)(9,10)(12,13)(14,15),
                 (1,2)(6,8)(7,11)(9,12)(10,14)(13,15)]);
R[10799]:=[];
RG[10799]:=[];
# Design 10799 / Resolution 1: autom. group order 5760, decomposable
R[10799][1]:=[[1,35,37,39],[2,36,38,40],[3,17,25,33],
              [4,18,26,34],[5,13,19,31],[6,14,20,32],
              [7,15,21,27],[8,16,22,28],[9,11,23,29],
              [10,12,24,30]];
RG[10799][1]:=Group([(5,16)(6,15)(7,14)(8,13)(9,12)(10,11),
                     (5,9)(6,10)(7,8)(11,15)(12,16)(13,14),
                     (5,7,6)(8,15,12)(9,14,11)(10,16,13),
                     (3,4)(6,7)(8,11)(9,12)(10,13)(14,15),
                     (2,3)(6,7)(8,15)(9,16)(10,14)(11,13),
                     (2,5)(3,7)(4,6)(8,11)(9,13)(10,12),
                     (1,2)(6,8)(7,11)(9,12)(10,14)(13,15)]);

This resolvable 2-(16,4,2) design has automorphism group order 5760 and a unique resolution.

Block data
The blocks of the design are:
D[10799]:=[[1,2,3,4],[1,2,3,4],[1,5,6,7],[1,5,6,7],
           [1,8,9,10],[1,8,9,10],[1,11,12,13],[1,11,12,13],
           [1,14,15,16],[1,14,15,16],[2,5,8,11],[2,5,8,11],
           [2,6,12,14],[2,6,12,14],[2,7,9,15],[2,7,9,15],
           [2,10,13,16],[2,10,13,16],[3,5,13,15],[3,5,13,15],
           [3,6,8,16],[3,6,8,16],[3,7,10,12],[3,7,10,12],
           [3,9,11,14],[3,9,11,14],[4,5,10,14],[4,5,10,14],
           [4,6,9,13],[4,6,9,13],[4,7,11,16],[4,7,11,16],
           [4,8,12,15],[4,8,12,15],[5,9,12,16],[5,9,12,16],
           [6,10,11,15],[6,10,11,15],[7,8,13,14],[7,8,13,14]];
(Note that there are repeated blocks.)
Automorphism group generators
Generator permutations for the automorphism group of the design are listed in cycle notation.
G[10799]:=Group([(5,6,7)(8,12,15)(9,11,14)(10,13,16),
                 (5,8,11)(6,9,13)(7,10,12)(14,15,16),
                 (3,4)(6,7)(8,11)(9,12)(10,13)(14,15),
                 (2,3)(6,7)(8,15)(9,16)(10,14)(11,13),
                 (2,5)(3,6)(4,7)(9,10)(12,13)(14,15),
                 (1,2)(6,8)(7,11)(9,12)(10,14)(13,15)]);
The generator sets given for the automorphism groups are in general not minimal.

Resolutions
Representatives of the nonisomorphic resolution(s) of the design are listed parallel class by parallel class together with their automorphism groups. For example,
R[10799][1]:=[[1,35,37,39],[2,36,38,40],[3,17,25,33],
              [4,18,26,34],[5,13,19,31],[6,14,20,32],
              [7,15,21,27],[8,16,22,28],[9,11,23,29],
              [10,12,24,30]];
RG[10799][1]:=Group([(5,16)(6,15)(7,14)(8,13)(9,12)(10,11),
                     (5,9)(6,10)(7,8)(11,15)(12,16)(13,14),
                     (5,7,6)(8,15,12)(9,14,11)(10,16,13),
                     (3,4)(6,7)(8,11)(9,12)(10,13)(14,15),
                     (2,3)(6,7)(8,15)(9,16)(10,14)(11,13),
                     (2,5)(3,7)(4,6)(8,11)(9,13)(10,12),
                     (1,2)(6,8)(7,11)(9,12)(10,14)(13,15)]);
says that the first parallel class of the first resolution consists of blocks 1, 35, 37, 39; the second parallel class of consists of blocks 2, 36, 38, 40, and so on. (Blocks are numbered in the order they are listed starting from 1.) So, R[10799][1] encodes the following resolution:
  [ [ 1, 2, 3, 4 ], [ 5, 9, 12, 16 ], [ 6, 10, 11, 15 ], [ 7, 8, 13, 14 ] ], 
  [ [ 1, 2, 3, 4 ], [ 5, 9, 12, 16 ], [ 6, 10, 11, 15 ], [ 7, 8, 13, 14 ] ], 
  [ [ 1, 5, 6, 7 ], [ 2, 10, 13, 16 ], [ 3, 9, 11, 14 ], [ 4, 8, 12, 15 ] ], 
  [ [ 1, 5, 6, 7 ], [ 2, 10, 13, 16 ], [ 3, 9, 11, 14 ], [ 4, 8, 12, 15 ] ], 
  [ [ 1, 8, 9, 10 ], [ 2, 6, 12, 14 ], [ 3, 5, 13, 15 ], [ 4, 7, 11, 16 ] ], 
  [ [ 1, 8, 9, 10 ], [ 2, 6, 12, 14 ], [ 3, 5, 13, 15 ], [ 4, 7, 11, 16 ] ], 
  [ [ 1, 11, 12, 13 ], [ 2, 7, 9, 15 ], [ 3, 6, 8, 16 ], [ 4, 5, 10, 14 ] ], 
  [ [ 1, 11, 12, 13 ], [ 2, 7, 9, 15 ], [ 3, 6, 8, 16 ], [ 4, 5, 10, 14 ] ], 
  [ [ 1, 14, 15, 16 ], [ 2, 5, 8, 11 ], [ 3, 7, 10, 12 ], [ 4, 6, 9, 13 ] ], 
  [ [ 1, 14, 15, 16 ], [ 2, 5, 8, 11 ], [ 3, 7, 10, 12 ], [ 4, 6, 9, 13 ] ]
(Note that there are repeated parallel classes.)

Designs (nonresolvable)

The format for the 2-(13,6,5) and 2-(14,7,6) designs is simpler. The blocks of the design are listed first, followed by a set of generator permutations for the full automorphism group.

Below is an example of a 2-(13,6,5) design.

# Design 9450: autom. group order 156, simple, derived
B[9450]:=[[1,2,3,4,5,6],[1,2,3,7,8,9],[1,2,4,7,10,11],[1,2,5,8,10,12],
          [1,2,9,11,12,13],[1,3,4,7,12,13],[1,3,5,10,11,13],[1,3,6,9,10,12],
          [1,4,5,8,9,11],[1,4,6,8,10,13],[1,5,6,7,9,13],[1,6,7,8,11,12],
          [2,3,4,9,10,13],[2,3,5,7,11,12],[2,3,6,8,11,13],[2,4,5,7,8,13],
          [2,4,6,8,9,12],[2,5,6,9,10,11],[2,6,7,10,12,13],[3,4,6,7,9,11],
          [3,4,8,10,11,12],[3,5,6,7,8,10],[3,5,8,9,12,13],[4,5,6,11,12,13],
          [4,5,7,9,10,12],[7,8,9,10,11,13]];
G[9450]:=Group([(2,3)(4,7)(5,9)(6,8)(10,12)(11,13),
                (2,4,3,7)(5,13,9,11)(6,12,8,10),
                (2,5,6,7,11,10,3,9,8,4,13,12),
                (1,2)(3,9)(4,12)(5,11)(6,13)(7,8)]);

Petteri Kaski (Petteri.Kaski@hut.fi)