[GAP Forum] Crime Package. Memory Question.

[Ellis, Grahamj]

The HAP package can also be used for cohomology rings. The following requires about 512Mb of memory and shows that there are five generators in degree 1, three generators in degree 2, and no generators in degrees 3,4,5.


gap> LoadPackage("hap");;
Loading HAP 1.8.8 ...
gap>  N:=SmallGroup(256,26973);;
gap> gens:=ModPCohomologyGenerators(N,5);;
gap> t:=time;;StringTime(t);
" 0:03:36.493"
gap> List(gens[1],gens[2]);
[ 0, 1, 1, 1, 1, 1, 2, 2, 2 ]


Graham




>I am trying to compute the cohomology ring of the
>SmallGroup=(256,26973);

>Using the crime package, but looks like I am having a memory error.

>When  run in windows, I do:

>C:\GAP4R4\bin\gapw95.exe -m 256m -o 3g -l C:\GAP4R4\ %1 %2 %3 %4 %5 %6 %7 %8

>gap> LoadPackage("crime");;
>gap> N:=SmallGroup(256,26973);
>gap> C:=CohomologyObject(N);;
>gap> CohomologyGenerators(5);

>and after a time, the program said that can not extend the memory and
>finish. I can compute CohomologyGenerators(3); but no more.

>Whe I do it in linux, I do:

>gap -m 256m -o 16g
>gap> LoadPackage("crime");;
>gap> N:=SmallGroup(256,26973);
>gap> C:=CohomologyObject(N);;
>gap> CohomologyGenerators(5);

>Here the answer is: "Segmentatio fault". I have checked the memory, and
>looks like GAP is not using the whole memory of the computer (16G), just a
>2% or 3%.

>I really appreciate any help.

>Thank.