DIMENSIONS FOR RANDOM SELF-CONFORMAL SETS

1　IntroductionTherehasbeenconsiderableinterestinfractals,bothintheiroccurrenceinthesciences,andintheirmathematicaltheory .Awideclassoffractalsetsaregeneratedbyiteratedfunc tionsystem .Aself similarsetinRdisacompactsetKfulfillingtheinvarianceK =∪Ni=1 SiK ,whereS1,S2 ,… ,SNarecontractivesimilarities.IfS1,S2 ,… ,SNarecontractiveconfor malmappings,weobtainself conformalset.Itiswell known(seeHutchinson [1 2 ] )that,givenafamilyofsuchmappings,thereisauniquecompactsetwiththisproperty .Ifth…     

类切饼集的测度维数

本文考虑了满足一定条件的类切饼集,主要利用密度定理,获得其Hausdorff测度和填充测度是等价的.同时,给出这类类切饼集维数和测度的统计解释.     

Excellent扩张和弱维数

在这篇文章里，我们证明了，当环Ｓ是Ｒ的ｅｘｃｅｌｌｅｎｔ扩张，Ｍ是Ｓ－模时，Ｍ做为Ｓ－模的弱维数与Ｍ做为Ｒ－模的弱维数相等。     

环的优越扩张与凝聚维数

设Ｓ和Ｒ是环．本文证明了若下述条件之一成立，则Ｓ和Ｒ具有相同的凝聚维数：（１）Ｓ是Ｒ的优越扩张；（２）Ｓ和ＭＭｏｒｉｔａ等价．作为上述结果的推论，我们证明了环Ｒ和下述环类具有相同的凝聚维数：（ｉ）Ｒ上的矩阵环Ｍｎ（Ｒ）；（ｉ）Ｒ和有限群Ｇ（要求｜Ｇ｜－１∈Ｒ）的斜群环；（ｉｉ）Ｓｍａｓｈ积Ｒ＃Ｇ＊（要求Ｇ是有限群且｜Ｇ｜－１∈Ｒ，Ｒ是Ｇ分次环）     

正实数维分形集的构造方法

给出了测量一类分形集维数的简单方法. 根据这种测量方法, 可以构造出任意实数维分形集,并且分形集可以不是自相似的.     

THE DIMENSIONS OF THE RANGE OF RANDOM WALKS IN TIME-RANDOM ENVIRONMENTS

Suppose {Xn} is a random walk in time-random environment with state space Zd,|Xn| approaches infinity, then under some reasonable conditions of stability, the upper bound of the discrete Packing dimension of the range of {Xn} is any stability index a. Moreover, if the environment is stationary, a similar result for the lower bound of the discrete Hausdorff dimension is derived. Thus, the range is a fractal set for almost every environment.     

THE P-COTORSION DIMENSIONS OF MODULES AND RINGS

Let R be a ring. We define a dimension, called P-cotorsion dimension, for modules and rings. The aim of this article is to investigate P-cotorsion dimensions of modules and rings and the relations between P-cotorsion dimension and other homological dimensions. This dimension has nice properties when the ring in consideration is generalized morphic.     

Weak Global Dimension of Coherent Rings

In this article, we study the weak global dimension of coherent rings in terms of the left FP-injective resolutions of modules. Let R be a left coherent ring and ? ? the class of all FP-injective left R-modules. It is shown that wD(R) ≤ n (n ≥ 1) if and only if every nth ? ?-syzygy of a left R-module is FP-injective; and wD(R) ≤ n (n ≥ 2) if and only if every (n ? 2)th ? ?-syzygy in a minimal ? ?-resolution of a left R-module has an FP-injective cover with the unique mapping property. Some results for the weak global dimension of commutative coherent rings are also given.     

自相似集的一类子集的维数

设F是满足强分离条件的自相似集，A↓x∈F，必存在唯一的无穷序列σx=(σx^(1),…，σx^(k)…）∈{1,2,…，m}^N,与之对应，定义F的子集：Fm,c,r={x∈F|∑rj=1σx^n j≥c,n=0,1,2,…},其中c,r为任意取定的正整数，本文证明了fm,c,r是图递归集，并确定了Fm,c,r的Hausdorff维数。     

Envelopes and Covers by Modules of Finite FP-Injective Dimensions

Let R be a ring, n a fixed non-negative integer and ? the class of all left R-modules of FP-injective dimensions at most n. It is proved that all left R-modules over a left coherent ring R have ?-preenvelopes and ?-covers. Left (right) ?-resolutions and the left derived functors of Hom are used to study the FP-injective dimensions of modules and rings.     

具阻尼的非线性波动方程整体吸引子的Hausdorff维数、分形维数估计

本文得到了一类具有线性阻尼且非线性项满足临界增长条件的非线性波动方程整体吸引子的Hausdorff维数、分形维数估计．     

On Strongly Copure Flat Modules and Copure Flat Dimensions

Let R be a left coherent ring. We first prove that a right R-module M is strongly copure flat if and only if Ext ⁱ (M, C) = 0 for all flat cotorsion right R-modules C and i ≥ 1. Then we define and investigate copure flat dimensions of left coherent rings. Finally, we give some new characterizations of n-FC rings.     

相对n-FP-内射模

给出了n-FP-内射模的定义,M为左R-模,如果对任意的左R-模N有Ext1(N,M)=0,则称M为n-FP-内射模,作为应用,给出了n-FP-内射模的一些等价条件.     

形式级数域中具有某种连分数展式集合的Hausdorff维数

本文研究了形式级数域中若干连分数例外集.利用质量分布原理和构造特殊覆盖,得到了当连分数展式部分商的度分别以多项式速度和指数速度趋向无穷大时,分别对应例外集的Hausdorff维数.     

On Copure Projective Modules and Copure Projective Dimensions

Let R be any ring. A right R-module M is called n-copure projective if Ext¹(M, N) = 0 for any right R-module N with fd(N) ≤ n, and M is said to be strongly copure projective if Ext ⁱ (M, F) = 0 for all flat right R-modules F and all i ≥ 1. In this article, firstly, we present some general properties of n-copure projective modules and strongly copure projective modules. Then we define and investigate copure projective dimensions of modules and rings. Finally, more properties and applications of n-copure projective modules, strongly copure projective modules and copure projective dimensions are given over coherent rings with finite self-FP-injective dimension.     

Redefined generalized fuzzy ideals of near-rings

With a new idea, we redefine generalized fuzzy subnear-rings(ideals) of a near- ring and investigate some of its related properties. Some new characterizations are given. In particular, we introduce the concepts of strong prime(or semiprime) (∈,∈∨q)-fuzzy ideals of near-rings, and discuss the relationship between strong prime(or semiprime) (∈,∈∨q)-fuzzy ideals and prime(or semiprime) (∈,∈∨q)-fuzzy ideals of near-rings.     

Prethick Subcategories of Modules and Characterizations of Local Rings

This article studies characterizing local rings in terms of homological dimensions. The key tool is the notion of a prethick subcategory which we introduce in this article. Our methods recover the theorems of Salarian, Sather-Wagstaff, and Yassemi.     

带五次项的NLS方程及其谱逼近的整体吸引子的维数估计

通过给出一般发展方程和其近似方程解的整体吸引子的Hausdorff维数上界间的关系，继[1，2]的讨论，本文进一步得到了带五次项的NLS方程和半离散Fourier谱近似解的整体吸引子的Hausdorff维数的上界估计。