> < ^ Date: Wed, 29 Mar 1995 08:56:00 -0600
> ^ From: Walter Carlip <c3ar@math.uchicago.edu >
> ^ Subject: Memory Use

I'm puzzled by Gap's use of memory. I find that "Gasman"
fails to obtain "bags" for many computations
I attempt. Let me give a particular example.
I was investigating the cardinality of the set
{g | <A,g> has abelian Sylow 2-subgroup} as A ranges over
the conjugacy classes of subgroups of a group G and g
ranges over elements of G. I have Gap the group G = SymmetricGroup(6),
which is not too large (720). While Gap had no difficulty
computing the ConjugacyClassesSubgroups, or doing other computations
with G, it choked on my program:

Myvector := function(group,classes,prime)
  local A,g,i,v;    v:=[];
  for A in classes do
    i:= 0;
      for g in Elements(group) do
        if IsAbelian(SylowSubgroup(Closure(A.representative,g),prime)) then
          i:= i+1;

Question: Is Gap having difficulty with this because it attempts
to save every bit of information it computes, i.e., a list of
each subgroup <A,g> together with its sylow 2-subgroup? If this
is the problem, is there a way to tell Gap to discard intermediate
results (when known to be no longer needed)?


Walter C3arlip                          **** carlip@ace.cs.ohiou.edu ****
(the "3" is silent)                     **** c3ar@zaphod.uchicago.edu ****

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