Let I be a homogeneous ideal of a graded affine k–algebra R such that there exists some homogeneous minimal reduction. We prove that the degrees (of a basis) of every homogeneous minimal reduction J of I are uniquely determined by I; moreover if the fiber cone F(I) is reduced, then the last degree of J is equal to the last degree of I. Moreover, if R is Cohen–Macaulay and I is of analytic deviation one, with 0 < ht(I) := g, it is shown that the first g degrees of J are equals to the first g degrees of I. These results are applied to the ideals I of k[x_0, . . . , x_{d−1}], whichhave scheme–theoretic generations of length ht(I) + 2. Some examples are given.

Some remarks on homogeneous minimal reductions

SPANGHER, WALTER
2007-01-01

Abstract

Let I be a homogeneous ideal of a graded affine k–algebra R such that there exists some homogeneous minimal reduction. We prove that the degrees (of a basis) of every homogeneous minimal reduction J of I are uniquely determined by I; moreover if the fiber cone F(I) is reduced, then the last degree of J is equal to the last degree of I. Moreover, if R is Cohen–Macaulay and I is of analytic deviation one, with 0 < ht(I) := g, it is shown that the first g degrees of J are equals to the first g degrees of I. These results are applied to the ideals I of k[x_0, . . . , x_{d−1}], whichhave scheme–theoretic generations of length ht(I) + 2. Some examples are given.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2498945
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