ker -- Kernel of a homomorphism |
Syntax |
ker(phi: RINGHOM): IDEAL |
Description |
Example |
/**/ R ::= QQ[x,y,z,w]; /**/ Use S ::= QQ[s,t]; /**/ phi := PolyAlgebraHom(R, S, [s^3, s^2*t, s*t^2, t^3]); /**/ ker(phi); ideal(z^2 -y*w, y*z -x*w, y^2 -x*z) /**/ SmodJ := NewQuotientRing(S, "t+s"); /**/ use SmodJ; /**/ psi := PolyAlgebraHom(R, SmodJ, [s^3, s^2*t, s*t^2, t^3]); /**/ ker(psi); ideal(x +w, y -w, z +w) /**/ RmodI := NewQuotientRing(R, "x+y"); /**/ ker(InducedHom(RmodI, psi)); ideal((z +w), (y -w)) |
See Also |