4D Moser brute force search

From Polymath1Wiki
Jump to: navigation, search

The brute force search program requires first building a preliminary lookup table, and then a refined lookup table, to determine the Pareto-optimal statistics for all forbidden Level 2 sets. Details of the lookup table construction are here.

The basic idea is to run over pairs of Level 1 slices and Level 3 slices, which are 3D Moser sets. For each such pair, compute the forbidden Level 2 set, then use the lookup table to find the optimal statistics for that pair, add that to a global table of feasible (a,b,c,d,e) statistics for 4D Moser sets, and iterate. However, the total number of such pairs is [math]3813884 \times 3813884 \sim 1.4 \times 10^{13}[/math], which is computationally infeasible.

However, one can use symmetries to cut this number down. Look at the "a" corners of the Level 1 and Level 3 sets; these are two 8-bit strings (which we call the "a-signatures" of the Level1 and Level3 sets), so there are [math]2^{16}[/math] possible choices for these. Actually we can eliminate those choices for which a=1 and a=2, because if (0,b,c,d,e) is a feasible statistic then (1,b,c,d,e) and (2,b,c,d,e) is feasible also (just pick a "b", "c", "d", or "e" point which is not in the set, and then pick a pair of "a" points with that midpoint). In fact (3,b,c,d,e) is also feasible, see Lemma below.

For the remaining configurations, one exploits the symmetry group of [math][3]^4[/math], which has order [math]4! \times 2^4 = 384[/math]. There are 391 remaining equivalence classes; for each equivalence class, we pick a representative which minimises the number of Level1 x Level3 pairs. A table of these representatives can be found here. A table of how many Moser sets there are for each a-signature can be found here.

With these reductions, the number of pairs to check drops to 62 billion (or more precisely, 62009590818).

The code to scan the pairs is here. When compiled (say, as scan.exe), the format is

 scan x y

which will scan the signature-pair classes from x to y, where [math]0 \leq x \leq y \leq 390[/math], and output the relevant feasible statistics to stdout and to an output file. If instead one types

 scan x y count

then this will indicate what percentage of the scan range is covered by x to y.

In the case x=372 and y=390 (which only takes about a minute to run), here is the stdout output and file output (for testing purposes). The full file output can be found here.


Lemma Suppose that (0,b,c,d,e) is a feasible statistic for a 4D Moser set. Then (3,b,c,d,e) is also feasible.

Proof Let A be a 4D Moser set with statistics (0,b,c,d,e). It suffices to show that we can add three "a" points to A and still have a Moser set, i.e. one can find three "a" points whose three midpoints are omitted by A. We assume for contradiction that this is not possible.

Suppose first that A contains a "d" point, such as 2221. Then A must omit either 2211 or 2231; without loss of generality we may assume that it omits 2211. Similarly we may assume it omits 2121 and 1221. Then we can add 1131, 1311, 3111 to A, a contradiction. Thus we may assume that A contains no "d" points.

Now suppose that A omits a "c" point, such as 2211. Then one can add 3333, 3111, 1311 to A, a contradiction. Thus we may assume that A contains all "c" points, which in particular implies that A omits the "e" point 2222.

Since A contains all the "c" points, it must omit a "b" point, such as 2111. But then 3111, 1111, 3333 can be added to the set, a contradiction.

Pareto Maxima and Extremal Points

This routine was run on a Linux cluster, taking around two hours. The output files were collated, there were 390 Pareto maxima:

    3    16    24     0     0
    4    14    19     2     0
    4    15    24     0     0
    4    16     8     4     1
    4    16    14     4     0
    4    16    23     0     0
    4    17    21     0     0
    4    18    19     0     0
    5    12    12     4     1
    5    12    13     6     0
    5    12    15     5     0
    5    12    19     2     0
    5    13    10     4     1
    5    13    14     5     0
    5    13    21     1     0
    5    15     9     4     1
    5    15    12     3     1
    5    15    13     5     0
    5    15    18     3     0
    5    15    20     1     0
    5    15    22     0     0
    5    16     7     4     1
    5    16    10     3     1
    5    16    11     5     0
    5    16    12     2     1
    5    16    16     3     0
    5    16    19     1     0
    5    16    21     0     0
    5    17    12     4     0
    5    17    14     3     0
    5    17    16     2     0
    5    17    18     1     0
    5    17    20     0     0
    5    18    13     3     0
    5    18    14     2     0
    5    20     8     4     0
    5    20    10     3     0
    5    20    13     2     0
    5    20    14     1     0
    5    20    18     0     0
    5    21    10     2     0
    5    21    15     0     0
    5    22    13     0     0
    6     8    12     8     0
    6    10    11     4     1
    6    11    12     7     0
    6    12    10     7     0
    6    12    13     5     0
    6    12    18     4     0
    6    13    16     4     0
    6    14     9     4     1
    6    14     9     7     0
    6    14    12     6     0
    6    14    16     3     0
    6    14    19     1     0
    6    14    21     0     0
    6    15     7     4     1
    6    15    10     3     1
    6    15    10     6     0
    6    15    11     2     1
    6    15    12     5     0
    6    15    15     4     0
    6    15    20     0     0
    6    16     7     3     1
    6    16     8     6     0
    6    16     9     2     1
    6    16    10     5     0
    6    16    12     1     1
    6    16    13     4     0
    6    16    14     3     0
    6    16    18     2     0
    6    16    19     0     0
    6    17     9     5     0
    6    17    10     4     0
    6    17    13     3     0
    6    17    15     2     0
    6    17    17     1     0
    6    17    18     0     0
    6    18    13     2     0
    6    18    16     1     0
    6    18    17     0     0
    6    19     9     4     0
    6    19    12     3     0
    6    19    15     1     0
    6    20     7     4     0
    6    20     9     3     0
    6    20    12     2     0
    6    20    13     1     0
    6    20    15     0     0
    6    21     8     3     0
    6    21     9     2     0
    6    21    12     1     0
    6    21    14     0     0
    6    22     7     3     0
    6    22     8     2     0
    6    22    10     1     0
    6    23     9     1     0
    6    24     7     2     0
    6    24     8     1     0
    6    24    12     0     0
    6    25     9     0     0
    6    26     7     0     0
    7     8     6     8     0
    7    11     9     4     1
    7    11    12     6     0
    7    12     8     4     1
    7    12     8     6     0
    7    12    12     3     1
    7    12    12     5     0
    7    12    13     4     0
    7    12    15     3     0
    7    12    17     2     0
    7    13     7     4     1
    7    13    10     3     1
    7    13    11     5     0
    7    13    12     2     1
    7    13    12     4     0
    7    13    14     3     0
    7    13    16     2     0
    7    14     6     4     1
    7    14     6     7     0
    7    14     9     5     0
    7    14    10     2     1
    7    14    12     1     1
    7    14    17     1     0
    7    14    19     0     0
    7    15     7     5     0
    7    15     8     3     1
    7    15     9     2     1
    7    15    11     1     1
    7    15    11     4     0
    7    15    13     3     0
    7    15    16     1     0
    7    16     6     3     1
    7    16     6     6     0
    7    16     8     2     1
    7    16    10     1     1
    7    16    10     4     0
    7    16    12     0     1
    7    16    12     3     0
    7    16    15     2     0
    7    16    17     0     0
    7    17     6     5     0
    7    17     7     4     0
    7    17    11     3     0
    7    17    13     2     0
    7    17    14     1     0
    7    17    16     0     0
    7    18    10     3     0
    7    18    13     1     0
    7    18    15     0     0
    7    19     9     3     0
    7    20     6     4     0
    7    20    11     2     0
    7    20    12     1     0
    7    20    14     0     0
    7    21     8     2     0
    7    21    10     1     0
    7    21    12     0     0
    7    22     9     1     0
    7    22    11     0     0
    7    23     6     3     0
    7    23     7     1     0
    7    23    10     0     0
    7    24     6     2     0
    7    24     9     0     0
    7    25     6     1     0
    7    25     8     0     0
    7    26     3     1     0
    7    28     6     0     0
    7    29     3     0     0
    7    30     1     0     0
    8     8     0     8     0
    8     8     9     7     0
    8     8    12     6     0
    8     9     9     4     1
    8     9    10     6     0
    8     9    12     3     1
    8     9    12     5     0
    8     9    13     4     0
    8     9    15     3     0
    8    10     7     4     1
    8    10    10     3     1
    8    10    10     5     0
    8    10    12     2     1
    8    10    12     4     0
    8    10    13     3     0
    8    10    15     2     0
    8    11     6     4     1
    8    11     9     6     0
    8    11    10     2     1
    8    11    11     4     0
    8    12     7     6     0
    8    12     9     3     1
    8    12     9     5     0
    8    12    10     4     0
    8    12    12     1     1
    8    12    14     2     0
    8    12    16     1     0
    8    12    18     0     0
    8    13     7     3     1
    8    13     7     5     0
    8    13     9     2     1
    8    13    12     0     1
    8    13    12     3     0
    8    14     0     7     0
    8    14     6     6     0
    8    14     7     2     1
    8    14     8     1     1
    8    14     9     4     0
    8    14    11     0     1
    8    14    11     3     0
    8    14    13     2     0
    8    14    15     1     0
    8    14    17     0     0
    8    15     6     3     1
    8    15     6     5     0
    8    15     7     1     1
    8    16     0     6     0
    8    16     4     3     1
    8    16     4     5     0
    8    16     6     2     1
    8    16     8     4     0
    8    16     9     0     1
    8    16    10     3     0
    8    16    12     2     0
    8    16    14     1     0
    8    16    16     0     0
    8    17     0     5     0
    8    17     3     4     0
    8    17     8     3     0
    8    17    10     2     0
    8    17    12     1     0
    8    17    14     0     0
    8    18     9     2     0
    8    18    11     1     0
    8    18    12     0     0
    8    19     6     3     0
    8    19     8     2     0
    8    20     0     4     0
    8    20     4     3     0
    8    20     7     2     0
    8    20     9     1     0
    8    20    11     0     0
    8    21     4     2     0
    8    21     7     1     0
    8    22     3     2     0
    8    22     6     1     0
    8    22     9     0     0
    8    23     0     3     0
    8    23     4     1     0
    8    24     0     2     0
    8    24     3     1     0
    8    24     8     0     0
    8    25     1     1     0
    8    25     6     0     0
    8    26     0     1     0
    8    26     4     0     0
    8    28     3     0     0
    8    32     0     0     0
    9     8    10     4     0
    9     9     9     4     0
    9     9    12     3     0
    9    10     8     4     0
    9    10    10     3     0
    9    10    12     2     0
    9    10    13     1     0
    9    10    15     0     0
    9    11    11     2     0
    9    12     7     4     0
    9    12     9     3     0
    9    12    12     1     0
    9    12    14     0     0
    9    13     7     3     0
    9    13    10     2     0
    9    14     9     2     0
    9    14    11     1     0
    9    14    13     0     0
    9    15     6     3     0
    9    16     0     4     0
    9    16     4     3     0
    9    16     8     2     0
    9    16    10     1     0
    9    16    12     0     0
    9    17     3     3     0
    9    17     6     2     0
    9    17     8     1     0
    9    17    10     0     0
    9    18     2     3     0
    9    18     4     2     0
    9    18     7     1     0
    9    18     9     0     0
    9    19     0     3     0
    9    19     3     2     0
    9    19     6     1     0
    9    20     1     2     0
    9    20     5     1     0
    9    20     8     0     0
    9    21     4     1     0
    9    21     6     0     0
    9    22     1     1     0
    9    22     5     0     0
    9    24     4     0     0
    9    25     2     0     0
    9    28     0     0     0
   10     8     6     4     0
   10     8     8     3     0
   10     9     7     3     0
   10     9    10     2     0
   10     9    11     1     0
   10     9    13     0     0
   10    10     5     4     0
   10    10     9     2     0
   10    10    12     0     0
   10    11     6     3     0
   10    12     4     4     0
   10    12     5     3     0
   10    12     7     2     0
   10    12    10     1     0
   10    12    11     0     0
   10    13     6     2     0
   10    13     8     1     0
   10    13    10     0     0
   10    14     3     3     0
   10    14     5     2     0
   10    14     9     0     0
   10    15     2     3     0
   10    15     7     1     0
   10    16     4     2     0
   10    16     6     1     0
   10    16     8     0     0
   10    17     4     1     0
   10    17     6     0     0
   10    18     2     1     0
   10    18     5     0     0
   10    20     4     0     0
   10    21     2     0     0
   10    22     1     0     0
   10    24     0     0     0
   11     4     6     4     0
   11     6     5     4     0
   11     7     6     3     0
   11     8     4     4     0
   11     8     5     3     0
   11     9     6     2     0
   11     9     8     1     0
   11     9    10     0     0
   11    10     3     3     0
   11    10     5     2     0
   11    10     9     0     0
   11    11     2     3     0
   11    11     7     1     0
   11    12     4     2     0
   11    12     6     1     0
   11    12     8     0     0
   11    13     4     1     0
   11    13     6     0     0
   11    14     2     1     0
   11    14     5     0     0
   11    16     4     0     0
   11    17     2     0     0
   11    18     1     0     0
   11    20     0     0     0
   12     4     3     3     0
   12     6     2     3     0
   12     6     5     2     0
   12     6     7     1     0
   12     6     9     0     0
   12     8     4     2     0
   12     8     6     1     0
   12     8     8     0     0
   12     9     4     1     0
   12     9     6     0     0
   12    10     2     1     0
   12    10     5     0     0
   12    12     4     0     0
   12    13     2     0     0
   12    14     1     0     0
   12    16     0     0     0
   13     6     5     0     0
   13     8     4     0     0
   13     9     2     0     0
   13    10     1     0     0
   13    12     0     0     0
   14     4     3     0     0
   14     5     2     0     0
   14     6     1     0     0
   14     8     0     0     0
   15     4     0     0     0
   16     0     0     0     0

Using qhull, 58 extremals were found:

    3     16     24      0      0 
    4     14     19      2      0 
    4     15     24      0      0 
    4     16      8      4      1 
    4     16     14      4      0 
    4     18     19      0      0 
    5     12     12      4      1 
    5     12     19      2      0 
    5     13     21      1      0 
    5     15      9      4      1 
    5     15     12      3      1 
    5     15     18      3      0 
    5     16      7      4      1 
    5     16     10      3      1 
    5     16     12      2      1 
    5     20      8      4      0 
    5     20     18      0      0 
    5     21     10      2      0 
    6      8     12      8      0 
    6     10     11      4      1 
    6     12     18      4      0 
    6     14      9      4      1 
    6     14      9      7      0 
    6     14     12      6      0 
    6     14     21      0      0 
    6     15      7      4      1 
    6     16     18      2      0 
    7     12     12      3      1 
    7     14      6      4      1 
    7     14      6      7      0 
    7     16     12      0      1 
    7     30      1      0      0 
    8      8      0      8      0 
    8      8      9      7      0 
    8      8     12      6      0 
    8      9      9      4      1 
    8      9     12      3      1 
    8      9     15      3      0 
    8     10      7      4      1 
    8     10     12      2      1 
    8     11      6      4      1 
    8     11     10      2      1 
    8     12     12      1      1 
    8     12     18      0      0 
    8     13     12      0      1 
    8     14      0      7      0 
    8     14      6      6      0 
    8     14      8      1      1 
    8     15      6      3      1 
    8     15      7      1      1 
    8     16      4      3      1 
    8     16      6      2      1 
    8     16      9      0      1 
    8     16     16      0      0 
    8     26      0      1      0 
    8     32      0      0      0 
   11      8      4      4      0 
   16      0      0      0      0

A search for the linear equations bounding these points gave the following 145: Each row is of the form ax1 + bx2 + cx3 + dx4 + ex5 <= x6

         3          12          12          23          72         480
          1           4           4           4          35         160
          1           4           4           1          41         160
          0           0           1           0          12          24
          3          12          19          36         117         648
          0           0           2           3          12          48
          3          12          17          33         102         600
          0           3           2           5          12          96
         12          57          48          95         288        2064
          4          19          16          19         134         688
          4          19          16           4         164         688
          0           3           4           9          24         144
          0           3           2           3          18          96
          0           3           2           0          24          96
          3           4           4           7          24         168
          1           1           1           1           8          43
          2           2           2           3          13          86
          3           2           4           6          27         138
          6           2           9          12          60         270
          6           6           7          12          42         282
         20          14          15          18         106         650
          9           6           8          12          51         318
         27          18          20          24         141         858
         34          16          19          15         110         832
          7           2           4           4          20         154
          6           0           4           3          15         120
         18           6          11          12          60         426
         18           6          10           9          57         402
         11           4           6           5          35         248
          9           3           5           3          30         201
          3           0           2           0          12          60
         16           6           9           8          54         370
          0           0           0           0           1           1
          0           0           0           1           4           8
          0           1           1           3           8          44
          1           2           1           3          16          72
          3           8           5          15          40         280
          1           2           1           9          26         106
          7          14           7          29          80         504
          0           2           1           2          16          64
          0           1           0           0          16          32
          0           1           0           6          16          56
          0           7           0          18          40         224
          0           5           3           9          20         160
         10          15          14          25          84         602
          1           1           1           3           9          50
          9           6           8          18          57         342
          9           6           7          18          57         330
          1           0           1           3          13          42
          9           3          10          18          69         342
          5           2           3          10          37         162
          3           1           2           6          23          98
          2           2           1           3          19          80
          3           3           2           6          18         120
          2           2           1           9          27         112
         14          14           7          31          93         560
          6           9           7          15          42         336
          1           1           1           2           6          44
          2           2           1           2          22          80
          6           6           5           6          42         240
         30          21          19          27         138         912
          3           2           2           4          13          94
         15          10           8          19          62         440
          6           4           3           7          29         176
         21          14          12          25          82         616
         81          54          49          72         357        2376
         18          12           9          16         102         528
          3           3           1          15          44         174
          6           6           1          36         107         384
         21          21           7          51         146         840
          1           1           0           6          19          64
          1           1           0           3          10          43
         42          42           7         108         317        1680
          7           7           1          18          54         280
          2           1           1           1           6          48
          9           3           4           9          24         198
          2           1           1           3           9          56
          3           2           1           9          27         118
         30          12          11          39         117         720
         15           6           5          21          63         366
          3           1           1           3           8          62
          6           5           1          30          90         328
          6           2           1          12          36         160
          9           3           2          15          45         222
         12           3           2          18          51         264
          3           1           1           2           5          56
          4           1           2           2           9          80
          2           0           1           1           3          34
         16           3           6           8          21         272
         12           6           5          15          45         306
         39          24          17          51         153        1080
          3           2           1           5          15          90
         17          12           6          28          84         520
         15           9           7          18          57         408
          9           4           3           9          23         200
         33          24          11          57         169        1032
         21          14           7          33          97         616
         19           6          10           9          55         408
         15           5           8           5          47         328
          8           2           4           3          21         160
          4           1           2           1          11          80
          6           5           1          14          42         216
         66          63          11         162         478        2544
          8           3           4           4          24         176
          7           3           3           4          19         152
          6           2           3           3          17         128
         48          18          17          24         132         960
          8           3           3           4          20         160
          6           2           2           3          13         112
          9           3           2          12          36         201
          6           2           1           8          24         132
         12           3           2          12          33         222
          6           2           1           6          16         118
         18           7           3          18          46         368
          5           2           1           5          13         104
          3           1           1           1           7          56
         33          12          11          15          93         648
          6           3           2           3          30         144
         21           3           2          18          51         336
          1           0           0           1           4          16
         14           3           3           9          24         226
         56          11          12          36          97         896
         46           9           6          36          99         746
         56           9           6          46         129         896
          9           0           4           4          12         144
         18           3           6           8          21         288
          4           1           1           2           5          64
          1           0           0           0           8          16
         24           5           5          15          42         384
         16           3           2          12          35         256
          9           0           4           0          24         144
         12           2           4           3          21         192
          8           2           2           3          13         128
         21           4           2          16          48         336
         84          16           9          64         186        1344
          6           1           2           1          11          96
          4           1           1           1           7          64
         48          12          11          15          93         768
         26           6           3          18          48         418
         28           7           3          18          46         448
         28           6           3          20          56         448
          8           2           1           5          13         128
          8           2           1           2          22         128
         12           3           2           3          30         192
          4           1           0           0          16          64