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Let $A$ be a two-dimensional excellent normal Gorenstein local domain. In this paper, we characterize elliptic ideals $I \subset A$ for its normal tangent cone $\overline{G}(I)$ to be Gorenstein. Moreover, we classify all those ideals in a…

Commutative Algebra · Mathematics 2025-12-16 Tomohiro Okuma , Kei-ichi Watanabe , Ken-ichi Yoshida

We introduce the the normal reduction number of two-dimensional normal singularities and prove that elliptic singularity has normal reduction number two. We also prove that for a two-dimensional normal singularity which is not rational, it…

Algebraic Geometry · Mathematics 2025-12-16 Tomohiro Okuma

This paper purposes to characterize Noetherian local rings $(A, {\mathfrak m})$ of positive dimension such that the first Hilbert coefficients of ${\mathfrak m}$-primary ideals in $A$ range among only finitely many values. Examples are…

Commutative Algebra · Mathematics 2013-12-24 Asuki Koura , Naoki Taniguchi

In this paper, we introduce the notion of $p_g$-ideals and $p_g$-cycles, which inherits nice properties of integrally closed ideals on rational singularities. As an application, we prove an existence of good ideals for two-dimensional…

Commutative Algebra · Mathematics 2025-12-16 Tomohiro Okuma , Kei-ichi Watanabe , Ken-ichi Yoshida

In this paper, we give a formula for normal reduction number of an integrally closed $\mathfrak m$-primary ideal of a $2$-dimensional normal local ring $(A,\mathfrak m)$ in terms of the geometric genus $p_g(A)$ of $A$. Also we compute the…

Commutative Algebra · Mathematics 2025-12-16 Tomohiro Okuma , Kei-ichi Watanabe , Ken-ichi Yoshida

The authors introduced the notion of $p_g$-ideals for two-dimensional excellent normal local domain over an algebraicaly closed field in terms of resolution of singularities. In this note, we give several ring-theoretic characterization of…

Commutative Algebra · Mathematics 2025-12-16 Tomohiro Okuma , Kei-ichi Watanabe , Ken-ichi Yoshida

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. When $A$ contains an algebraically…

Commutative Algebra · Mathematics 2018-08-29 Tony J. Puthenpurakal

Let $(A, \mathfrak m)$ be a normal two-dimensional local ring and $I$ an $\mathfrak m$-primary integrally closed ideal with a minimal reduction $Q$. Then we calculate the numbers: $\mathrm{nr}(I) = \min\{n \;|\; \overline{I^{n+1}} =…

Commutative Algebra · Mathematics 2025-12-16 Tomohiro Okuma , Kei-ichi Watanabe , Ken-ichi Yoshida

The notion of $p_g$-ideals for normal surface singularities has been proved to be very useful. On the other hand, the core of ideals has been proved to be very important concept and also very mysterious one. However, the computation of the…

Algebraic Geometry · Mathematics 2025-12-16 Tomohiro Okuma , Kei-ichi Watanabe , Ken-ichi Yoshida

There has arisen in recent years a substantial theory of "multiplier ideals'' in commutative rings. These are integrally closed ideals with properties that lend themselves to highly interesting applications. But how special are they among…

Commutative Algebra · Mathematics 2007-05-23 Joseph Lipman , Keiichi Watanabe

We survey some of the major results about normal Hilbert polynomials of ideals. We discuss a formula due to Lipman for complete ideals in regular local rings of dimension two, theorems of Huneke, Itoh, Huckaba, Marley and Rees in…

Commutative Algebra · Mathematics 2012-05-16 Mousumi Mandal , Shreedevi Masuti , J. K. Verma

Let $(R,\mathfrak m)$ be an analytically unramified local ring of positive prime characteristic $p.$ For an ideal $I$, let $I^*$ denote its tight closure. We introduce the tight Hilbert function $H^*_I(n)=\ell(R/(I^n)^*)$ and the…

Commutative Algebra · Mathematics 2020-08-19 Kriti Goel , Vivek Mukundan , J. K. Verma

In this paper we consider extremal and almost extremal bounds on the normal Hilbert coefficients of ${\mathfrak m}$-primary ideals of an analytically unramified Cohen-Macaulay ring $R$ of dimension $d>0$ and infinite residue field. In these…

Commutative Algebra · Mathematics 2014-10-17 Alberto Corso , Claudia Polini , Maria Evelina Rossi

Given a local Cohen-Macaulay ring $(R, {\mathfrak m})$, we study the interplay between the integral closedness -- or even the normality -- of an ${\mathfrak m}$-primary $R$-ideal $I$ and conditions on the Hilbert coefficients of $I$. We…

Commutative Algebra · Mathematics 2007-05-23 Alberto Corso , Claudia Polini , Maria Evelina Rossi

Let A be a local ring with maximal ideal m. For an arbitrary ideal I of A, we define the generalized Hilbert coefficients j_k(I) \in Z^{k+1} (k=0,1,...,dim A). When the ideal I is m-primary, j_k(I)=(0,...,0,(-1)^k e_k(I)), where e_k(I) is…

Commutative Algebra · Mathematics 2007-05-23 Catalin Ciuperca

Let $(A,\mathfrak{m})$ be an excellent normal domain of dimension two containing a field $k \cong A/\mathfrak{m}$. 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 $k$…

Commutative Algebra · Mathematics 2023-03-14 Tony J. Puthenpurakal

Let $(R, m)$ be a $d$-dimensional Cohen-Macaulay local ring. In this note we prove, in a very elementary way, an upper bound of the first normalized Hilbert coefficient of a $m$-primary ideal $I\subset R$ that improves all known upper…

Commutative Algebra · Mathematics 2019-05-01 Juan Elias

This paper gives an upper bound of the second Hilbert coefficients ${\mathrm{e}}_2(I)$ of $\mathfrak{m}$-primary ideals $I$ in a Cohen-Macaulay local ring $(A,{\mathfrak{m}})$ in terms of the sectional genera of $I$.

Commutative Algebra · Mathematics 2014-04-22 Kazuho Ozeki

Let $(R, \mathfrak{m})$ be a regular local ring of characteristic $p > 0$. Among all proper ideals $\mathfrak{a}\subseteq R$ with a fixed order of vanishing $\text{ord}_{\mathfrak{m}}(\mathfrak{a})$, we classify the ideals for which the…

Commutative Algebra · Mathematics 2026-01-28 Benjamin Baily

Let $A$ be an excellent two-dimensional normal local ring containing an algebraically closed field. Then $A$ is called an elliptic singularity if $p_f(A)=1$, where $p_f$ denotes the fundamental genus. On the other hand, the concept of…

Commutative Algebra · Mathematics 2024-11-01 Tomohiro Okuma , Kei-ichi Watanabe , Ken-ichi Yoshida
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