[GAP Forum] Constructing bilinear maps for matrix multiplication

[Lisette Brillemans]

> > It's just this kind of things that surpise me as well. In one of my
> > earlier posts a few days ago I stated that
> >
> > ListX(Combinations(a,2),Combinations(a,2),\>,pair); works but
> >
> > ListX(Combinations(a,2),Combinations(a,2),\<,pair); doesn't.
> >
> > (of course a and pair are defined separately)
> >
> > Which is unlogical as well.
> >
> > Your IsAlgebraWithOne(S); should be true of course.
> 
> Regarding \< and \>: it is a > b if and only if b < a, so GAP needs only
> one of the operations \<, \>. If both operations would exist, always for both
> of them methods would need to be installed -- one of them just 'for nothing'.

I hope you don't mind that I write a reply on this again. 

What doesn't work either is:


a:=[1,2,3,4];
pair:=function(x,y); return[x,y]; end;
> 
ListX(Combinations(a,2),Combinations(a,2),\<\>,pair)

So I tried:

not ListX(Combinations(a,2),Combinations(a,2),\=,Pair)

which leads to:

Variable: 'Pair' must have a value.

[I am still surprised about this, because /> does work (As already asked
and answered upon.]


So, \< isn't entirely "for nothing" because now "\<\>" doesn't work
either. And using "not" isn't a solution for that. 

Or am I seeing this wrongly?


Best regards,


Lisette