Resolutions of monomial almost complete intersections and generalizations

Let S=K[x₁,…,x_n] be a polynomial ring over a field kand let / be a monomial ideal of S. The main result of this paper is an explicit minimal resolution of kover R= S/Iwhen / is a monomial almost complete intersection ideal of S. We also compute an upper bound on the multigraded resolution of k over a generalization of monomial almost complete intersection ring.     

On stability of the monomial functional equation in normed spaces over fields with valuation

A stability theorem is proved for the monomial functional equation where the functions map a normed space over a field of characteristic zero with an arbitrary valuation into a Banach space over a field of characteristic zero with a valuation. Some regularity properties of the monomial functions are also discussed.     

On the equations defining monomial curves

Let C be a monomial curve in three dimensional projective space over an algebraically closed field K of characteristic zero . We give several necessary criterions for C to be set theoretic complete intersection. Using these criterions we get several restrictions concerning the form of the equations that define C set theoretically.     

单边单项式序下的SAGBI基

设K是一个域,R是具有SM-基B的一个K-代数,且是B上一个单边（即左或右）单项式序.那么关于交换多项式代数和非交换自由代数的子代数在双边单项式序下经典的SAGBI基理论可完整地推广到R的子代数上来.特别地,对于一类N-分次代数,存在计算有限n-截断SAGBI基的有效算法,并且第一次阐明了在单边单项式序下讨论SAGBI...     

On the arithmetically cohen-macaulay property for monomial curves

Let C be a monomial curve in three dimensional projective space over a field of characteristic zero . We give a necessary criterion for a monomial curve to be set theoretic complete intersection on bihomogeneous surfaces. Using this criterion we prove several results concerning the arithmetically Cohen-Macaulay property for monomial curves.     

Monomial Hopf algebras over fields of positive characteristic

In this paper, we study the structures of monomial Hopf algebras over a field of positive characteristic. A necessary and sufficient condition for the monomial coalgebra Cd(n) to admit Hopf structures is given here, and if it is the case, all graded Hopf structures on Cd(n) are completely classified. Moreover, we construct a Hopf algebras filtration on Cd(n) which will help us to discuss a conjecture posed by Andruskiewitsch and Schneider. Finally combined with a theorem by Montgomery, we give the structure theorem for all monomial Hopf algebras.     

Uniform modules over serial rings with krull dimension

We study the symbolic blow-up ring of a prime ideal defining a monomial curve in the power series ring in 3 variables over a field. We characterize the conditions required to have the symbolic blow-up generated in degree 4 when the monomial curve is non-self-linked. When this is the case we also find that the symbolic blow-up cannot be Cohen–Macaulay.     

Generation in Degree Four of Symbolic Blowups of Self-Linked Monomial Space Curves

We study the symbolic blowup ring of a prime ideal defining a monomial curve in the power series ring in 3 variables over a field. We characterize the conditions required to have the symbolic blowup generated in degree 4 when the monomial curve is self-linked.     

Hadamard定理在四元数体上的推广

Let K be any skew-field with central field F. A matrix A=(a_ij)n×n over K is called centralized if the characteristic matrix λI-A can be reduced by some elementary transformations into the following diagonal form:such that are all manic polynomials over F. The determinant of a centralized matrix A=(a_ij)n×n may be defined by (1) asfollows: and then the famous theorem of Hadamard can be generalized as in the following: Theorem. If A=(a_ij)n×n is a non-singular centralized matrix over the skewfield of quaternions, thenand the equality sign holds if and only if the columns of A are all muturally orthogonal. This theorem may be proved by the following three lemmas: Lemma 1. If A is a centralized n-rowed square matrix of quaternions, then sois and Lemma 2. For any n-rowed square, matrix A of quaternions, the. following two matrices are always centralized:and Lemma 3. If A is a centralized matrix of quaternions, then we have     

Bases for rings of coinvariants

We study the multiplicative structure of rings of coinvariants for finite groups. We develop methods that give rise to natural monomial bases for such rings over their ground fields and explicitly determine precisely which monomials are zero in the ring of coinvariants. We apply our methods to the Dickson, upper triangular and symmetric coinvariants. Along the way, we recover theorems of Steinberg [17] and E. Artin [1]. Using these monomial bases we prove that the image of the transfer for a general linear group over a finite field is a principal ideal in the ring of invariants. This research is supported in part by the Natural Sciences and Engineering Research Council of Canada     

On the fiber cone of monomial ideals

Archiv der Mathematik - We consider the fiber cone of monomial ideals. It is shown that for monomial ideals $$I\subset K[x,y]$$ of height 2, generated by 3 elements, the fiber cone F(I) of I is a...     

Weak toroidalization over non-closed fields

We prove that any dominant morphism of algebraic varieties over a field k of characteristic zero can be transformed into a toroidal (hence monomial) morphism by projective birational modifications of source and target. This was previously proved by the first and third author when k is algebraically closed. Moreover we show that certain additional requirements can be satisfied.     

On the Stanley depth of weakly polymatroidal ideals

Let ${\mathbb{K}}$ be a field and ${S = \mathbb{K}[x_1,\dots,x_n]}$ be the polynomial ring in n variables over the field ${\mathbb{K}}$ . In this paper, it is shown that Stanley’s conjecture holds for I and S/I if I is a product of monomial prime ideals or I is a high enough power of a polymatroidal or a stable ideal generated in a single degree.     

The Category of Firm Modules for Nonunital Monomial Algebras

Let k be a field and X a set and P be a set of words over X. Consider the free nonunital k-algebra over X generated by the nonempty words over X and let R be the quotient of this algebra modulo the ideal generated by the words in P. R is called a “nonunital monomial algebra”. A right R-module M is said to be “firm” if M? _R R → M given by m ? r? mr is an isomorphism. In this article we prove that if R is a nonunital monomial algebra, the category of firm modules is Grothendieck.     

A Simple Note on the Yoneda (CO)Algebra of a Monomial Algebra

Ukrainian Mathematical Journal - If A = TV/hRi is a monomial K-algebra, then it is well known that $$ {Tor}_p^A $$ (K,K) is isomorphic to the space V(p−1) of (Anick) (p − 1)-chains for...     

Explicit volume-preserving splitting methods for polynomial divergence-free vector fields

We present new, explicit, volume-preserving splitting methods for polynomial divergence-free vector fields of arbitrary degree (both positive and negative). The main idea is to decompose the divergence polynomial by means of an appropriate basis for polynomials: the monomial basis. For each monomial basis function, the split fields are then identified by collecting the appropriate terms in the vector field so that each split vector field is volume preserving. We show that each split field can be integrated exactly by analytical methods. Thus, the composition yields a volume preserving numerical method. Our numerical tests indicate that the methods compare favorably to standard integrators both in the quality of the numerical solution and the computational effort.     

Serre's Condition Rℓ for Affine Semigroup Rings

In this note we characterize the affine semigroup rings K[S] over an arbitrary field K that satisfy condition R_? of Serre. Our characterization is in terms of the face lattice of the positive cone pos(S) of S. We start by reviewing some basic facts about the faces of pos(S) and consequences for the monomial primes of K[S]. After proving our characterization we turn our attention to the Rees algebras of a special class of monomial ideals in a polynomial ring over a field. In this special case, some of the characterizing criteria are always satisfied. We give examples of non-normal affine semigroup rings that satisfy R₂.