[GAP Forum] Curious behavior of IsAlgExtRep

[Alexander Hulpke]

Dear Forum,

On May 13, 2013, at 5/13/13 4:39, "Ha T. Lam" <hatlam at gmail.com> wrote:

> I encountered a curious behavior when I tried to use IsAlgExtRep:
> 
> x:=Indeterminate(GF(2), "x");
> f:=x^5+x^3+Z(2)^0;
> gf:=GF(2,f);
> prim:=PrimitiveElement(gf);
> IsAlgExtRep(prim);
> 
> In the above code, I expected IsAlgExtRep(prim) to return true, but it
> tells me that it's false instead. If I change the polynomial to:

IsAlgExtRep indicates whether an element is represented internally as element of a formal (quotient of polynomial ring) algebraic extension. Fields of order <=2^16 are represented using Zech logarithms, thus they are not IsAlgExtRep (their representation is `IsInternalRep').

Regards,

   Alexander Hulpke

-- Colorado State University, Department of Mathematics,
Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
http://www.math.colostate.edu/~hulpke