Weighted Least-Squares Polynomial Deflation

We present a unified analysis of several methods of polynomialdeflation, including methods commonly in use. We also discussthe suitability of "minimum-norm" deflations and present theresults of numerical tests on a new method.     

Sum-Free Sets and Related Sets

A   of integers is sum-free if . Cameron conjectured that the number of sum-free sets is . As a step towards this conjecture, we prove that the number of sets satisfying

随机模糊集与随机集

本文研究了三个方面的工作：一是定义了一种模糊集上的可测结构，从而定义了随机模糊集，这些定义都与论域Ｘ上的拓扑结构无关。将通常意义下的集合看成特殊模糊集得到的通常集合上的超可测结构与文（３）中的定义一致；二是给出了随机模糊集、随机集的一些等价条件；三是研究了随机模糊集、随机集的分布与其有限维落影族的关系。     

Large Sets and Overlarge Sets of Triangle-Decomposition

There are six types of triangles:undirected triangle,cyclic triangle,transitive triangle,mixed-1triangle,mixed-2 triangle and mixed-3 triangle.The triangle-decompositions for the six types of triangles havealready been solved.For the first three types of triangles,their large sets have already been solved,and theiroverlarge sets have been investigated.In this paper,we establish the spectrum of LT_i(v,λ),OLT_i(v)(i=1,2),and give the existence of LT_3(v,λ)and OLT_3(v,λ)with λ even.     

A NEW Method of Polynomial Deflation

Previous results on a weighted least-squares approach to polynomialdeflation are exploited to produce a new method. The new methodis shown to preserve zeros exactly. Numerical tests are reportedwhich indicate that this property holds good in practice.     

Major Sets,Classes of Simple Sets,and $$Q $$ -Complete Sets

Each nonrecursive recursively enumerable set is proved to have a $Q$ -complete major subset. Classes of simple sets that contain $Q$ -complete sets are determined.     

Complementary Sets of Finite Sets

Subsets 𝒜, 𝒮 of an additive group G are complementary if 𝒜 + 𝒮 = G. When 𝒜 is of finite cardinality ∣𝒜∣, and G is ℤ or ℝ, we give sufficient conditions for the existence of a complementary set 𝒮 with “density” not much larger than 1/∣𝒜∣.     

Complementary Sets of Finite Sets

Subsets 𝒜, 𝒮 of an additive group G are complementary if 𝒜 + 𝒮 = G. When 𝒜 is of finite cardinality ∣𝒜∣, and G is ℤ or ℝ, we give sufficient conditions for the existence of a complementary set 𝒮 with “density” not much larger than 1/∣𝒜∣. Supported in part by NSF DMS-0074531. Received February 14, 2002; in revised form July 18, 2002 RID="a" ID="a" Dedicated to Professor Edmund Hlawka on the occasion of his 85th birthday     

Deflation in Krylov subspace methods and distance to uncontrollability

The task of extracting from a Krylov decomposition the approximation to an eigenpair that yields the smallest backward error can be phrased as finding the smallest perturbation which makes an associated matrix pair uncontrollable. Exploiting this relationship, we propose a new deflation criterion, which potentially admits earlier deflations than standard deflation criteria. Along these lines, a new deflation procedure for shift-and-invert Krylov methods is developed. Numerical experiments demonstrate the merits and limitations of this approach. This author has been supported by a DFG Emmy Noether fellowship and in part by the Swedish Foundation for Strategic Research under the Frame Programme Grant A3 02:128.     

可变模糊集合理论与可变模型集

在对立模糊集定义基础上给出以相对隶属函数表示的模糊可变集合定义,给出可变模糊聚类迭代模型、可变模糊模式识别模型、可变模糊对立识别模型.它们是可变模糊聚类、识别、优选决策、评价相统一的理论模型集,是可变模糊集的基础模型与核心内容,可用于自然、管理、人文、社会等各种学科中关于模糊聚类、识别、优选决策、评价、预测等众多实际领域.     

Sets satisfying the Central Sets Theorem

Central subsets of a discrete semigroup S have very strong combinatorial properties which are a consequence of the Central Sets Theorem . We investigate here the class of semigroups that have a subset with zero Følner density which satisfies the conclusion of the Central Sets Theorem. We show that this class includes any direct sum of countably many finite abelian groups as well as any subsemigroup of (?,+) which contains ?. We also show that if S and T are in this class and either both are left cancellative or T has a left identity, then S×T is in this class. We also extend a theorem proved in (Beiglböck et al. in Topology Appl., to appear), which states that, if p is an idempotent in β? whose members have positive density, then every member of p satisfies the Central Sets Theorem. We show that this holds for all commutative semigroups. Finally, we provide a simple elementary proof of the fact that any commutative semigroup satisfies the Strong Følner Condition.     

Translating Finite Sets into Convex Sets

Let X be a reflexive Banach space, and let C X be a closed,convex and bounded set with empty interior. Then, for every > 0, there is a nonempty finite set F X with an arbitrarilysmall diameter, such that C contains at most .|F| points ofany translation of F. As a corollary, a separable Banach spaceX is reflexive if and only if every closed convex subset ofX with empty interior is Haar null. 2000 Mathematics SubjectClassification 46B20 (primary), 28C20 (secondary).     

基于粗糙集与模糊集的信息检索算法

结合粗糙集与模糊集理论,提出一种信息检索的新方法.该方法首先对已知文本信息按关键词进行模糊聚类;然后利用粗糙集理论求出各关键词的重要性程度;最后根据最大相似度原则对文本信息进行检索,若结果集中文本数量较大,则按文本与已知文本的相似度从高到低进行排序,先返回相似度较高的相关文档.     

The Automorphism Conjecture for Small Sets and Series Parallel Sets

The automorphism conjecture for ordered sets states that the automorphism to endomorphism ratio will tend to zero as the size of the ordered set goes to infinity. We show by computer enumeration that up to size 11 the ratio is largest for weakly ordered sets. Subsequently, we derive exact recursive formulas for the number of homomorphisms between two related types of weakly ordered sets and we prove a strong automorphism conjecture for series-parallel ordered sets. We conclude with an example that shows that the automorphism to endomorphism ratio can exceed for arbitrarily large .This work was sponsored by Louisiana Board of Regents RCS grant LEQSF(1999-02)-RD-A-27.     

Determining Sets, Resolving Sets, and the Exchange Property

A subset U of vertices of a graph G is called a determining set if every automorphism of G is uniquely determined by its action on the vertices of U. A subset W is called a resolving set if every vertex in G is uniquely determined by its distances to the vertices of W. Determining (resolving) sets are said to have the exchange property in G if whenever S and R are minimal determining (resolving) sets for G and ${r\in R}$ , then there exists ${s\in S}$ so that ${S-\{s\} \cup \{r\}}$ is a minimal determining (resolving) set. This work examines graph families in which these sets do, or do not, have the exchange property. This paper shows that neither determining sets nor resolving sets have the exchange property in all graphs, but that both have the exchange property in trees. It also gives an infinite graph family (n-wheels where n ≥ 8) in which determining sets have the exchange property but resolving sets do not. Further, this paper provides necessary and sufficient conditions for determining sets to have the exchange property in an outerplanar graph.     

粗糙模糊集与模糊粗糙集的截集性质

研究粗糙模糊集、模糊粗糙集、广义粗糙模糊集和广义模糊粗糙集的截集性质,并且还研究了基于逻辑算子的广义模糊粗糙集的基本性质。     

模糊粗糙集及粗糙模糊集的模糊度

1965年,Zadeh提出了Fuzzy集理论,1982年,Z.Pawlak提出Rough集理论。将二者结合而形成的模糊粗糙集（FR集）及粗糙模糊集（RF集）近年来越来越受到国际学术界的关注。本文所研究的FR集及RF集的模糊度,是对FR集及RF集模糊程度的一种度量,进而引进了相应的明可夫斯基距离,明可夫斯基模糊度和Shannon模糊度。     

Tight Gabor Sets on Discrete Periodic Sets

This paper addresses Gabor analysis on a discrete periodic set. Such a scenario can potentially find its applications in signal processing where signals may present on a union of disconnected discrete index sets. We focus on the Gabor systems generated by characteristic functions. A sufficient and necessary condition for a set to be a tight Gabor set in discrete periodic sets is obtained; discrete periodic sets admitting a tight Gabor set are also characterized; the perturbation of tight Gabor sets is investigated; an algorithm to determine whether a set is a tight Gabor set is presented. Furthermore, we prove that an arbitrary Gabor frame set can be represented as the union of a tight Gabor set and a Gabor Bessel set.     

Distance Sets of Well-Distributed Planar Point Sets

We prove that a well-distributed subset of ${\Bbb R}^2$ can have a distance set $\Delta$ with $\#(\Delta\cap [0,N])\leq CN^{3/2-\epsilon}$ only if the distance is induced by a polygon $K$. Furthermore, if the above estimate holds with $\epsilon=\frac12$, then $K$ can have only finitely many sides.