On Two Results of Mixed Multiplicities

Positivity of mixed multiplicities

This paper studies mixed multiplicities of an arbitrary standard bigraded algebra and mixed multiplicities of two ideals I, J in a local ring (A,m), where I is an m-primary ideal and J an arbitrary ideal. The main results are criteria for their positivity which can be used to compute them effectively. We also show that the range of positive mixed multiplicities of a bigraded algebra is rigid if the algebra satisfies the first chain condition and is connected in codimension one and that this range is always rigid for mixed multiplicities of ideals. These results can be used to study the mu-inva…

Mixed Multiplicities of Filtrations

In this paper we define and explore properties of mixed multiplicities of (not necessarily Noetherian) filtrations of $m_R$-primary ideals in a Noetherian local ring $R$, generalizing the classical theory for $m_R$-primary ideals. We construct a real polynomial whose coefficients give the mixed multiplicities. This polynomial exists if and only if the dimension of the nilradical of the completion of $R$ is less than the dimension of $R$, which holds for instance if $R$ is excellent and reduced. We show that many of the classical theorems for mixed multiplicities of $m_R$-primary ideals hold fo…

Mixed multiplicities of Divisorial Filtrations

Suppose that $R$ is an excellent local domain with maximal ideal $m_R$. The theory of multiplicities and mixed multiplicities of $m_R$-primary ideals extends to (possibly non Noetherian) filtrations of $R$ by $m_R$-primary ideals, and many of the classical theorems for $m_R$-primary ideals continue to hold for filtrations. The celebrated theorems involving inequalities continue to hold for filtrations, but the good conclusions that hold in the case of equality for $m_R$-primary ideals do not hold for filtrations. In this article, we consider multiplicities and mixed multiplicities of $R$ by $m…

Mixed multiplicities and projective degrees of rational maps

We consider the notion of mixed multiplicities for multigraded modules by using Hilbert series, and this is later applied to study the projective degrees of rational maps. We use a general framework to determine the projective degrees of a rational map via a computation of the multiplicity of the saturated special fiber ring. As specific applications, we provide explicit formulas for all the projective degrees of rational maps determined by perfect ideals of height two or by Gorenstein ideals of height three.

On mixed multiplicities of ideals

Let R be the local ring of a point on a variety X over an algebraically closed field k. We make a connection between the notion of mixed (Samuel) multiplicity of m-primary ideals in R and intersection theory of subspaces of rational functions on X which deals with the number of solutions of systems of equations. From this we readily deduce several properties of mixed multiplicities. In particular, we prove a (reverse) Alexandrov-Fenchel inequality for mixed multiplicities due to Teissier and Rees-Sharp. As an application in convex geometry we obtain a proof of a (reverse) Alexandrov-Fenchel in…

Mixed multiplicities, Hilbert polynomials and homaloidal surfaces

We investigate the relationship among several numerical invariants associated to a (free) projective hypersurface $V$: the sequence of mixed multiplicities of its Jacobian ideal, the Hilbert polynomial of its Milnor algebra, and the sequence of exponents when $V$ is free. As a byproduct, we obtain explicit equations for some of the homaloidal surfaces in the projective 3-dimensional space constructed by C. Ciliberto, F. Russo and A. Simis.

A Note on Formulas Transmuting Mixed Multiplicities

This paper establishes mixed multiplicity formulas concerning the relationship between mixed multiplicities of modules and mixed multiplicities of rings via rank of modules.

Mixed Multiplicities of Multi-Graded Algebras Over Noetherian Local Rings

Let S be a finitely generated standard multi-graded algebra over a Noetherian local ring A. This paper first expresses mixed multiplicities of S in term of Hilbert-Samuel multiplicity that explained the mixed multiplicities S as the Hilbert-Samuel multiplicities for quotient modules of S. As an application, we get formulas for the mixed multiplicities of ideals that covers the main result of Trung-Verma 2007 [TV].

The Recursion Formula for Mixed Multiplicities with respect to Joint Reductions

This paper gives the recursion formula for mixed multiplicities of maximal degrees with respect to joint reductions of ideals, which is one of important results in the mixed multiplicity theory. Using this result, we give consequences on the relationship between mixed multiplicities and the Hilbert-Samuel multiplicity under most essential assumptions, that is a substantial progress in the problem of expressing mixed multiplicities into the Hilbert-Samuel multiplicity.

On the Euler-Poincaré characteristic and mixed multiplicities of maximal degrees

This paper defines the Euler-Poincaré characteristic of joint reductions of ideals which concerns the maximal terms in the Hilbert polynomial; characterizes the positivity of mixed multiplicities in terms of minimal joint reductions; proves the additivity and other elementary properties for mixed multiplicities. The results of the paper together with the results of [17] seem to show a natural and nice picture of mixed multiplicities of maximal degrees.

Mixed multiplicities and the multiplicity of rees modules of reductions (published in j. Algebra appl.)

This paper shows that mixed multiplicities and the multiplicity of Rees modules of good filtrations and that of their reductions are the same. As an application of this result, we obtain interesting results on mixed multiplicities and the multiplicity of Rees modules.

A note on joint reductions and mixed multiplicities

Let $(A, \frak m)$ be a noetherian local ring with maximal ideal $\frak{m}$ and infinite residue field $k = A/\frak{m}.$ Let $J$ be an $\frak m$-primary ideal, $I_1,...,I_s$ ideals of $A$, and $M$ a finitely generated $A$-module. In this paper, we interpret mixed multiplicities of $(I_1,..., I_s,J)$ with respect to $M$ as multiplicities of joint reductions of them. This generalizes the Rees's theorem on mixed multiplicity (Theorem 2.4). As an application we show that mixed multiplicities are also multiplicities of Rees's superficial sequences.

Mixed Multiplicities of Maximal Degrees (J. Korean Math. Soc. 55 (2018), No. 3, 605-622)

The original mixed multiplicity theory considered the class of mixed multiplicities concerning the terms of highest total degree in the Hilbert polynomial. This paper defines a broader class of mixed multiplicities that concern the maximal terms in this polynomial, and gives many results, which are not only general but also more natural than many results in the original mixed multiplicity theory.

The Euler-Poincare characteristic and mixed multiplicities

This paper defines mixed multiplicity systems; the Euler-Poincare characteristic and the mixed multiplicity symbol of $\mathbb{N}^d$-graded modules with respect to a mixed multiplicity system, and proves that the Euler-Poincare characteristic and the mixed multiplicity symbol of any mixed multiplicity system of the type $(k_1,\ldots,k_d)$ and the $(k_1,\ldots,k_d)$-difference of the Hilbert polynomial are the same. As an application, we get results for mixed multiplicities.

Homology, mixed multiplicities and Fiber Cone

In this paper we study the Hilbert coefficients the fiber cone. We also compare the depths of the fiber cone and the associated graded ring.

Mixed Buchsbaum--Rim Multiplicities

We prove the results about mixed Buchsbaum--Rim multiplicities announced in (9.10)(ii) on p.224 of our recent paper [J.Alg.(1994)], including a general mixed-multiplicity formula. In addition, we identify these multiplicities as the coefficients of the ``leading form'' of the appropriate Buchsbaum-Rim polynomial in three variables, and we prove a positivity theorem. In fact, we define the multiplicities as the degrees of certain zero-dimensional ``mixed twisted'' Segre classes, and we develop an encompassing general theory of these new rational equivalence classes in all dimensions. In paralle…

Toward mixed multiplicities and joint reductions

In the direction towards the question when mixed multiplicities are equal to the Hilbert-Samuel multiplicity of joint reductions, this paper not only generalizes [28, Theorem 3.1] that covers the Rees's theorem [13, Theorem 2.4], but also removes the hypothesis that joint reductions are systems of parameters in [28, Theorem 3.1]. The results of the paper seem to make the problem of expressing mixed multiplicities into the Hilbert-Samuel multiplicity of joint reductions become closer.

Filter-regular sequences and mixed multiplicities

Let $S$ be a finitely generated standard multigraded algebra over an Artinian local ring $A$; $M$ a finitely generated multigraded $S$-module. This paper answers to the question when mixed multiplicities of $M$ are positive and characterizes them in terms of lengths of $A$-modules. As an application, we get results on mixed multiplicities of ideals (Proposition 4.4 and Theorem 4.5), and recover the results of Risler and Teissier [Te](see Remark 4.8), Trung and Verma [TV](see Remark 4.6).

An inequality in mixed multiplicities

The theory of mixed multiplicities of (not necessarily Noetherian) filtrations of $m_R$-primary ideals in a Noetherian local ring $R$, has been developed by Cutkosky, Sarkar and Srinivasan. The objective of this article is to generalise a Minkowski type inequality given in their paper. We also recover a result of Cutkosky, Srinivasan and Verma as a simple consequence of our inequality

Convex bodies and graded families of monomial ideals

We show that the mixed volumes of arbitrary convex bodies are equal to mixed multiplicities of graded families of monomial ideals, and to normalized limits of mixed multiplicities of monomial ideals. This result evinces the close relation between the theories of mixed volumes from convex geometry and mixed multiplicities from commutative algebra.

(FC)-Sequences, Mixed Multiplicities and Reductions of Modules

Let $(R, \mathfrak m)$ be a Noetherian local ring. In this work we use the notion of (FC)-sequences, as defined in \cite{perez-bedregal1}, to present some results concerning reductions and the positivity of mixed multiplicities of a finite collection of arbitrary submodules of $R^p.$ We also investigate the length of maximal (FC)-sequences. We actually work in the more general context of standard graded $R$-algebras.

Lojasiewicz exponent of families of ideals, Rees mixed multiplicities and Newton filtrations

We give an expression for the Łojasiewicz exponent of a wide class of n-tuples of ideals $(I_1,..., I_n)$ in $Ø_n$ using the information given by a fixed Newton filtration. In order to obtain this expression we consider a reformulation of Łojasiewicz exponents in terms of Rees mixed multiplicities. As a consequence, we obtain a wide class of semi-weighted homogeneous functions $(\mathbb{C}^n,0)\to (\mathbb{C},0)$ for which the Łojasiewicz of its gradient map $\nabla f$ attains the maximum possible value.

A Survey of Some Results for Mixed Multiplicities

The paper proves that the superficial sequences in [13, 15, 16, 25] are the weak-(FC)-sequences in [18]. This follows that [18, Theorem 3.4] of Viet in 2000 covers the results of Risler and Teissier [13] in 1973; Trung [15, Theorem 3.4] in 2001; Trung and Verma [16, Theorem 1.4] in 2007. The paper unified the results for mixed multiplicities of ideals in [13, 15, 16, 17, 18, 25].

计算混合重数、混合体积与截面Milnor数的算法

Algorithms for computing mixed multiplicities, mixed volumes and sectional Milnor numbers

本研究推出MixedMultiplicity程序包，通过推广Cox等人的成果获取理想多重Rees代数的定义方程，可计算诺特环理想混合重数，还能求解凸格点多面体混合体积与孤立奇点超曲面的截面Milnor数。

Multiplicities and Mixed Multiplicities of arbitrary Filtrations

We develop a theory of multiplicities and mixed multiplicities of filtrations, extending the theory for filtrations of $m$-primary ideals to arbitrary (not necessarily Noetherian) filtrations. The mixed multiplicities of $r$ filtrations on an analytically unramified local ring $R$ come from the coefficients of a suitable homogeneous polynomial in $r$ variables of degree equal to the dimension of the ring, analogously to the classical case of the mixed multiplicities of $m$-primary ideals in a local ring. We prove that the Minkowski inequalities hold for arbitrary filtrations. The characterizat…

Mixed multiplicities of arbitrary modules

Let $(R, \mathfrak m)$ be a Noetherian local ring. In this work we extend the notion of mixed multiplicities of modules, given in \cite{Kleiman-Thorup2} and \cite{Kirby-Rees1} (see also \cite{Bedregal-Perez}), to an arbitrary family $E,E_1,..., E_q$ of $R$-submodules of $R^p$ with $E$ of finite colength. We prove that these mixed multiplicities coincide with the Buchsbaum-Rim multiplicity of some suitable $R$-module. In particular, we recover the fundamental Rees's mixed multiplicity theorem for modules, which was proved first by Kirby and Rees in \cite{Kirby-Rees1} and recently also proved by…

计算混合重数、混合体积与截面Milnor数

Computing mixed multiplicities, mixed volumes, and sectional Milnor numbers

本文为综述性工作，介绍了基于推广Cox等人结果的多重Rees代数方程计算的Macaulay2新算法，可高效计算诺特环理想混合重数、凸格点多胞体混合体积与孤立奇点超曲面的截面Milnor数。

On some multiplicity and mixed multiplicity formulas (Forum Math. 26(2014), 413-442)

This paper gives the additivity and reduction formulas for mixed multiplicities of multi-graded modules $M$ and mixed multiplicities of arbitrary ideals, and establishes the recursion formulas for the sum of all the mixed multiplicities of $M.$ As an application of these formulas we get the recursion formulas for the multiplicity of multi-graded Rees modules.

Multiplicities in the mixed trace cocharacter sequence of two $3\times 3$ matrices

We find explicitly the multiplicities in the (mixed) trace cocharacter sequence of two $3\times 3$ matrices over a field of characteristic 0 and show that asymptotically they behave as polynomials of seventh degree. As a consequence we obtain also the multiplicities of certain irreducible characters in the cocharacter sequence of the polynomial identities of $3\times 3$ matrices.

通过混合Buchsbaum-Rim重数构造模的Minkowski型不等式与Rees逆命题的反例

Counterexamples to Minkowski-type inequalities and the Rees converse for modules via mixed Buchsbaum-Rim Multiplicities

本文构造混合Buchsbaum-Rim重数，证明其系数乘积公式，给出Minkowski型不等式等失效的反例，明确一维情形下Rees逆命题不成立，仅在特定条件下成立，并提出高维逆命题问题。

模的联合约化与混合 Buchsbaum-Rim 重数及联合约化数零定理

Joint reductions and mixed Buchsbaum-Rim multiplicities of modules and a joint-reduction-number-zero theorem

本文提出了 Noetherian 局部环上模的联合约化与混合 Buchsbaum-Rim 重数的新定义，证明了二维正则局部环上整闭模的联合约化数零定理，并揭示了模的混合重数与 Koszul 复形特征及理想重数间的联系。

在分次代数中计算 epsilon 重数

Computing epsilon multiplicities in graded algebras

本文研究了分次代数中 $\varepsilon$-重数的计算问题，证明了二维标准分次整环中齐次理想 $\varepsilon$-重数的有理性，给出了基于混合重数的计算公式，并提供了 Macaulay2 算法。

弱 Lefschetz 性质与单项式理想的混合重数

The weak Lefschetz property and mixed multiplicities of monomial ideals

本文利用等生成单项式理想的分析扩张、混合重数与双有理单项式映射的联系，以关联理想的混合重数给出平方自由约化满足弱 Lefschetz 性质的充要条件，并推广至正特征情形。

混合重数和分次族的Rees定理及其逆定理

Mixed multiplicities and Rees Theorems for graded families and their converses

本文针对Noetherian局部环上的分次族，引入弱渐近与强齐次联合约化，推广Rees混合重数定理及其逆定理，并导出Böger型定理，同时指出弱渐近逆定理的失效反例。

局部环中的重数与次数函数：通过相交积

Multiplicities and degree functions in local rings via intersection products

本文通过定义诺特局部环上真双有理概形的相交积，证明了里斯次数函数定理的新证明，并推广了拉马努詹公式以计算希尔伯特-塞缪尔重数，进而用相交理论表达混合重数及其多重线性性质。

The Minkowski Equality for Filtrations

Suppose that R is an analytically irreducible or excellent local domain with maximal ideal m_R. We consider multiplicities and mixed multiplicities of R by filtrations of m_R-primary ideals. We show that the theorem of Teissier, Rees and Sharp, and Katz, characterizing equality in the Minkowski inequality for multiplicities of ideals, is true for divisorial filtrations, and for the larger category of bounded filtrations. This theorem is not true for arbitrary filtrations of m_R-primary ideals.

多重分次代数与多重分次线性系

Multigraded algebras and multigraded linear series

本文研究多重分次代数与多重分次线性系，定义体积函数并建立其与整体牛顿-奥昆科夫体纤维体积的关联，证明可分解分次下体积函数为非负系数多项式，定义混合重数并刻画其正性，统一了混合重数领域的相关结果。

When are multidegrees positive?

Let $k$ be an arbitrary field, $P = P_k^{m_1} \times_k \cdots \times_k P_k^{m_p}$ be a multiprojective space over $k$, and $X \subseteq P$ be a closed subscheme of $P$. We provide necessary and sufficient conditions for the positivity of the multidegrees of $X$. As a consequence of our methods, we show that when $X$ is irreducible, the support of multidegrees forms a discrete algebraic polymatroid. In algebraic terms, we characterize the positivity of the mixed multiplicities of a standard multigraded algebra over an Artinian local ring, and we apply this to the positivity of mixed multiplicit…

关于张量特征值重数的新猜想

New conjectures on multiplicities of tensor eigenvalues

研究关于张量特征值重数的两个猜想，借助代数几何语言给出更强版本并在多新情况证明，尤其针对特定张量，还建立了张量秩与零特征值重数的联系。

Lengths and multiplicities of integrally closed modules over a two-dimensional regular local ring

Let $(R,{\bf m})$ be a two-dimensional regular local ring with infinite residue field. We prove an analogue of the Hoskin-Deligne length formula for a finitely generated, torsion-free, integrally closed $R$-module $M$. As a consequence, we get a formula for the Buchsbaum-Rim multiplicity of $F/M$, where $F = M^{**}$.

Frobenius重数及格拉斯曼二平面簇的F-签名

Frobenius multiplicities and F-signatures of Grassmannians of two-planes

本文给出了格拉斯曼簇Gr(2,n)的Plücker坐标环的Frobenius重数矩阵的非递归公式，证明其元素为p的多项式，从而得到F-签名等为p的有理函数，并给出Gr(2,4)等的具体表达式。

The Multivariate Fundamental Theorem of Algebra and Algebraic Geometry

We derive two consequences of the multivariate fundamental theorem of algebra (MFTA). The first one is the Bezout theorem for $n$ polynomials. Notably the intersection multiplicities, as in MFTA, are characterized just by means of partial differential operators given by polynomials from $D$-invariant linear spaces. The second consequence provides a solution to the ideal membership problem, based on the above characterization of intersection multiplicities. Let us mention that one readily gets Nullstellensatz from here.