[GAP Forum] homomorphism construction wanted

[Peter Brooksbank]

Hi Graham,

I'm guessing you know about the "NC" option at the end of certain commands
that prevents GAP from checking if an element lies where it is supposed to.
E.g.

GroupHomomorphismByImagesNC

So therefore I'm guessing that what you're really asking is whether such a
variant exists for the specific homomorphism function you are trying to
use. I don't see anything in the manual that suggests there is.

Perhaps the more knowledgeable community will weigh in shortly and say
something more useful.

Best,

Pete

On Sun, Apr 12, 2020 at 8:32 AM Ellis, Grahamj <graham.ellis at nuigalway.ie>
wrote:

> Dear GAP Community,
>
> Is there a way to construct a group homomorphism using a variant of the
> function
>
> f:=GroupHomomorphismByFunction(G,H,x->function(x))
>
> for which
>
> ImageElm(f,x)
>
> does not test to see if x lies in G?  Here function(x) is a well-defined
> function for x in G, but G is a group for which I don't have a membership
> test.
>
> Thanks,
>
> Graham
>
>
> School of Mathematics, Statistics & Applied Mathematics
> National University of Ireland, Galway
> tel: 091 493011
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-- 
*Peter A. Brooksbank*
*Professor of Mathematics*
*Bucknell University*