//---[CLO, p. 309]
//---Specialization of Groebner bases
ring r=0,(c1,s1,c2,s2,a,b,l2,l3),(dp(4),dp); //product order
option(redSB);

ideal id=l3*(c1*c2-s1*s2)+l2*c1-a,
l3*(c1*s2+c2*s1)+l2*s1-b,
c1^2+s1^2-1,c2^2+s2^2-1;

ideal j = std(id);
j;

//---[CLO, p. 309, line 16] should be corrected as follows:
// 2*l_2l_3, a^2+b^2, b, a, 2*l_2l_3, 2*l_2l_3, 2*l_2l_3, 1, l_3,
// l_2, l_3, l_2, 1.