Hello all,
I am currently trying to use GAP to compute the first homology of some
large-index congruence subgroups in arithmetic Kleinian groups. Large
primes often occur in the order of the torsion subgroup of such homology
and this causes the computation to be stalled by the inefficiency of the
factoring method ("FactorsInt") use in the function "AbelianInvariants".
For example a computation lasted for more than three hours (after the
group presentation was obtained) because of the failure to factor the
integer
105023714400084996151549919196232398687915731 = 8882788338909318083641 *
11823282329046290928491
(the number of "RhoTrials" kept augmenting but the algorithm failed to
terminate). On the other hand the factorisation above was almost
immediately computed by the function "Factors" after loading the package
"FactInt".
So I was wondering whether there is a simple way to force the function
AbelianInvariants to use the latter method of factorisation, or a
package with a function computing abelianisation of a group when large
primes occur in the invariants.
Cheers,
Jean Raimbault.
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