[GAP Forum] Indeterminates and GroupRing elements

[tkohl at math.bu.edu]

Dear forum members,

I am trying to do the following with GroupRing()

gap> QC3:=GroupRing(Rationals,Group((1,2,3)));;
gap> x:=Indeterminate(Rationals,"x");;
gap> y:=Indeterminate(Rationals,"y");;
gap> z:=Indeterminate(Rationals,"z");;
gap> B:=Basis(QC3);;
gap> Elements(B);
[ (1)*(), (1)*(1,2,3), (1)*(1,3,2) ]

So far so good, but the following doesn't work.

gap> h := x*B[1]+y*B[2]+y*B[3]
Error, no method found! For debugging hints type ?Recovery from NoMethodFound
Error, no 1st choice method found for `*' on 2 arguments called from
<function "HANDLE_METHOD_NOT_FOUND">( <arguments> )
 called from read-eval loop at line 32 of *stdin*
you can 'quit;' to quit to outer loop, or
you can 'return;' to continue

I want to do things like compute nilpotents etc by taking powers
of 'generic' elements of a group ring (like h above) which will 
yield equations in the coefficients of the basis elements of the group ring.

What is the correct way to do this?

Thanks.

	-Tim Kohl
         Boston University