MultiprojectiveVariety \ MultiprojectiveVariety -- difference of multi-projective varieties

i1 : R = ZZ/101[x_0,x_1,x_2,y_0,y_1,Degrees=>{3:{1,0},2:{0,1}}];

i2 : X = projectiveVariety ideal(x_0^3*y_0+2*x_0^2*x_1*y_0+2*x_0*x_1^2*y_0+x_1^3*y_0+2*x_0^2*x_2*y_0+3*x_0*x_1*x_2*y_0+2*x_1^2*x_2*y_0+2*x_0*x_2^2*y_0+2*x_1*x_2^2*y_0+x_2^3*y_0+x_0^3*y_1+2*x_0^2*x_1*y_1+2*x_0*x_1^2*y_1+x_1^3*y_1+2*x_0^2*x_2*y_1+3*x_0*x_1*x_2*y_1+2*x_1^2*x_2*y_1+2*x_0*x_2^2*y_1+2*x_1*x_2^2*y_1+x_2^3*y_1);

o2 : ProjectiveVariety, surface in PP^2 x PP^1

i3 : Y = projectiveVariety ideal(x_0*y_0+x_1*y_0+x_2*y_0+x_0*y_1+x_1*y_1+x_2*y_1);

o3 : ProjectiveVariety, surface in PP^2 x PP^1

i4 : Z = X \ Y;

o4 : ProjectiveVariety, surface in PP^2 x PP^1

i5 : assert(Z + Y == X and X \ Z == Y)