[GAP Forum] IsomorphismPermGroup behaves nondeterministically?

[Ignat Soroko]

Hello everybody,

I have a finite quotient group Q of an infinite finitely presented
group, which has order 2359296. I noticed that in different GAP
sessions if I call IsomorphismPermGroup(Q) I get different results and
different running times, ranging from

1.2 seconds, modest memory usage, permutations of degree 64, to
25 min, 60Gb of memory(!) used, permutations of degree 192,
and at some other times, I got permutations of degree 384.

Is it an intended behavior or some sort of a bug? Notice that I am not
invoking a method SmallerDegreePermutationRepresentation, which is
said to have randomized behavior. Is there a way to ensure
deterministic results for this function which can be reproduced by
others on different platforms?

Thank you!

Best wishes,
Ignat Soroko
https://www.math.lsu.edu/~ignatsoroko/