> < ^ From:

> < ^ Subject:

>

> > No relators are stored in the record. GAP knows how to compute with

> > the group g, which is a Klein four-group as expected, so

> >

> > gap> Comm(g.1, g.2);

> > IdAgWord

> >

> > works, but why are relators not written in the record describing g? I

> > know I can put the relators in explicitly by doing

>

> Each ag word carries a pointer to a data structure <D> created by

> 'AgGroupFpGroup'. The right hand sides of all power-commutator

> relations are stored in this data structure <D>, but in such a way that

> they need less space for non-trivial entries than the relators in

> abstract generators and no (extra) space for trivial entries.

> Creating the presentation in abstract generators would require a vast

> amount of space, 28 bytes for each trivial relator.

>

> best wishes

> Frank

>

> PS: To be precise: power-conjugates relations for single and tuple

> collectors and power-commutator relations for combinatorial collectors

> are stored in <D>.

>

>

But how can I see the relations of an ag group G that I read in from

e.g. the library of solvable groups or the library of 2-groups?

I want to find out how the generators G.1, ... correspond to the ones

in a presentation of G I have in another list of solvable groups,

or to correspond them to another description of G as e.g.

a semidirect product, or some other extension.

Ralf Dentzer

P.S. Is there a function to test for isomorphism between two

ag groups? This would maybe solve my problem, but I

did not find such a function. Moreover this functions

should also provide an isomorphism mapping generators

of one group to as short as possible expressions in

the generators of the second group.

P.P.S What I am doing now is guessing the correspondance and

verifying the relations I know, but this is rather

tedious.

> < [top]