//SINGULAR Example 3.5.5




ring R=0,(x,y,z),dp;
ideal I=yz,xz;
indepSet(std(I));
indepSet(std(I),1);

ring A  = 0,(x,y,t),dp;
ideal I = y2-x3-3t2x2;
indepSet(std(I),1);          

LIB"surf.lib";
plot(lead(I),"clip=cube;");
plot(I,"rot_x=1.4; rot_y=3.0; rot_z=1.44;");          //see Fig. 3.6