TR
- Give a non-commutative polynomial in the variables U and V, this function exchanges U and V by other polynomials, for example
gap>TR(U*V, [V,U]);
gap>(1)*V*U;
- That is TR(pol, [X,Y]) have the same effect of the endomorphism U --> X and V --> Y applied to pol;
- This functions calls other functions: SUBS.
TR:=function(pol, ltr)
local polaux;
polaux:=SUBS(pol, [U, T]);
polaux:=SUBS(polaux, [V, ltr[2]]);
polaux:=SUBS(polaux, [T, ltr[1]]);
return polaux;
end;