Here are spectra of a few smallest Equal-size Subsets (ESS).
|
|
|
2 ess 4 |
2 ess 6 |
3 ess 6 |
|
|
2 ess 8 |
4 ess 8 |
|
3 ess 9 |
The code generating ESS by RogerHui and Jordan Tirrell was posted in J Forum.
perm=: i.@! A. i.
ess2=: 4 : 0
~. (~.i.])"1 (perm y){"_ 1 (y%x)#i.x
)
require 'viewmat media/platimg gl2'
coinsert 'jgl2'
glqall=: (|. $ [:glqpixels 0 0&,)@glqwh
glwh=: 3 : 'wd''pmovex '',(+0 0,y-glqwh_jgl2_@$@#)&.".wd''qformx'''
viewwh=: ([:glwh(*|.@$)) ] viewmat@]
qw=: (glqall bind '' writeimg ]) [ wd bind'msgs'
Note 'Spectra'
30 viewwh |:2 ess2 4
qw'2x4.png'
20 viewwh |:2 ess2 6
qw'2x6.png'
20 viewwh |:3 ess2 6
qw'3x6.png'
10 viewwh |:2 ess2 8
qw'2x8.png'
4 10 viewwh |:4 ess2 8
qw'4x8.png'
3 10 viewwh |:3 ess2 9
qw'3x9.png'
)