[GAP Forum] How to increase memory?

[Alexander Hulpke]

Dear Forum,

Just in addition to Joe Bohanon's email:

If you get an error message ``exceeded memory'' and enter the break loop (respectively, exit it in the ggap shell) you can continue with `return;', respectively just start the calculation again witrh double the permited memory limit. There also is a hard limit (error message ``cannot extend memory'') due to the cygwin environment we're using -- see the section ``memory issues' at
http://www.gap-system.org/Download/WinInst.html

> On to the bigger question of getting maximal subgroups of S12, using the
> standard algorithms that GAP has is going to make it quite a challenge. To

The maximal subgroups for Sn and An, n<=50 are predefined in the library (using the result via the O'Nan-Scott theorem):

gap> g:=SymmetricGroup(12);
Sym( [ 1 .. 12 ] )
gap> MaximalSubgroupClassReps(g);
[ Alt( [ 1 .. 12 ] ), Group([ (1,2,3,4,5,6,7), (1,2), (8,9,10,11,12), (8,9) ])
    , Group([ (1,2,3,4,5,6,7,8), (1,2), (9,10,11,12), (9,10) ]), 
  Group([ (1,2,3,4,5,6,7,8,9), (1,2), (10,11,12), (10,11) ]), 
  Group([ (1,2,3,4,5,6,7,8,9,10), (1,2), (11,12) ]), 
  Group([ (1,2,3,4,5,6,7,8,9,10,11), (1,2) ]), 
  <permutation group of size 46080 with 8 generators>, 
  <permutation group of size 31104 with 10 generators>, 
  <permutation group of size 82944 with 8 generators>, 
  Group([ (1,2,3,4,5,6), (1,2), (7,8,9,10,11,12), (7,8), 
      (1,7)(2,8)(3,9)(4,10)(5,11)(6,12) ]), PGL(2, 11) ]

Best,

   Alexander Hulpke

-- Colorado State University, Department of Mathematics,
Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
http://www.math.colostate.edu/~hulpke