|This article is about a function from ApCoCoA-2. If you are looking for the ApCoCoA-1 version of it, see ApCoCoA-1:SB.Sagbi and ApCoCoA-1:SB.ReducedSagbi.|
Computes a finite SAGBI-basis of a subalgebra if existing.
SB.SAGBI(G:LIST of POLY):LIST of POLY
This function computes a finite SAGBI-basis of a subalgebra S generated by the polynomials of the list G, if a finite SAGBI-basis of S is existing. Then a list of polynomials is returned which form a SAGBI-basis of S. Otherwise the computation runs until it is interrupted.
@param G A list of polynomials which generates a subalgebra.
@return A list of polynomials which form a finite SAGBI-basis of the subalgebra generated by G.
Use QQ[x,y,z], DegRevLex; S := SB.SAGBI([x^2 -z^2, x*y +z^2, y^2 -2*z^2]); indent(S); -- [ -- y^2 -2*z^2, -- x*y +z^2, -- x^2 -z^2, -- x^2*z^2 +x*y*z^2 +(1/2)*y^2*z^2 +(-1/2)*z^4 -- ]