Let f0, f1, f2, f3 be linearly independent homogeneous quadratic forms in the standard Z-graded ring R := K[s, t, u], and gcd(f0, f1, f2, f3) = 1. This defines a rational map Ф : P2 → P3. The Rees algebra Rees(...Let f0, f1, f2, f3 be linearly independent homogeneous quadratic forms in the standard Z-graded ring R := K[s, t, u], and gcd(f0, f1, f2, f3) = 1. This defines a rational map Ф : P2 → P3. The Rees algebra Rees(I) = R I I2 … of the ideal I = (f0, fl, f2, fs) is the graded R-algebra which can be described as the image of an R-algebra homomorphism h : R[x, y, z, w] → Rees(I). This paper discusses the free resolutions of I, and the structure of ker(h).展开更多
文摘Let f0, f1, f2, f3 be linearly independent homogeneous quadratic forms in the standard Z-graded ring R := K[s, t, u], and gcd(f0, f1, f2, f3) = 1. This defines a rational map Ф : P2 → P3. The Rees algebra Rees(I) = R I I2 … of the ideal I = (f0, fl, f2, fs) is the graded R-algebra which can be described as the image of an R-algebra homomorphism h : R[x, y, z, w] → Rees(I). This paper discusses the free resolutions of I, and the structure of ker(h).