[GAP Forum] How to compute the image of a variable under a map

[Huta Gana]

Dear GAP forum,

I have run the following codes:





*gap> k:=GF(2^2);;gap>T:=MappingByFunction(k,k,t->t^2);;gap>
x:=Indeterminate(k,"x");gap> Image(T,x);Error, usage: Image(<map>),
Image(<map>,<elm>), Image(<map>,<coll>)*

It appears the error because  x is not an element of k

*gap> x in k;*
*false*

Could you show me how to compute the image of a variable under a map?

Thank you very much.

Best regards,

Huta