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On \(p_g\)-ideals. (English) Zbl 1454.13007

Summary: Let \((A,\mathfrak{m})\) be an excellent normal domain of dimension two. We define an \(\mathfrak{m}\)-primary ideal \(I\) to be a \(p_g\)-ideal if the Rees algebra \(A[It]\) is a Cohen-Macaulay normal domain. If \(A\) has infinite residue field then it follows from a result of Rees that the product of two \(p_g\) ideals is \(p_g\). When \(A\) contains an algebraically closed field \(k\cong A/\mathfrak{m}\) then Okuma, Watanabe and Yoshida [T. Okuma et al., Manuscr. Math. 150, No. 3–4, 499–520 (2016; Zbl 1354.13011)] proved that \(A\) has \(p_g\)-ideals and furthermore product of two \(p_g\)-ideals is a \(p_g\) ideal. In this article we show that if \(A\) is an excellent normal domain of dimension two containing a field \(k\cong A/\mathfrak{m}\) of characteristic zero then also \(A\) has \(p_g\)-ideals.

MSC:

13A30 Associated graded rings of ideals (Rees ring, form ring), analytic spread and related topics
13B22 Integral closure of commutative rings and ideals
13A50 Actions of groups on commutative rings; invariant theory
14B05 Singularities in algebraic geometry

Citations:

Zbl 1354.13011