On Convergence Approach Spaces

The extension of two axioms due to Cook and Fischer to the category CAP of convergence approach spaces leads to the study of non-Archimedean approach spaces as well as two versions of regularity appropriate to CAP and related categories.     

Approach Spaces, Limit Tower Spaces, and Probabilistic Convergence Spaces

The category LTS of limit tower spaces is defined and shown to be isomorphic to the category CAP of convergence approach spaces. The full subcategory of LTS determined by the objects satisfying a diagonal axiom due to Cook and Fischer is shown to be isomorphic to the category AP of approach spaces. A family of isomorphisms is also obtained between LTS and certain full subcategories of the category PCS of probabilistic convergence spaces.     

Approach Theory in Merotopic, Cauchy and Convergence Spaces. II

We define the notions of approach-Cauchy structure and ultra approach-Cauchy structure. We study the categorical properties of ACHY and uACHY and show that in these schemes Cauchy spaces and extended pseudo-(ultra)metric spaces are regarded as entities of the same kind. Furthermore, we investigate the relation with convergence-approach spaces and obtain a relationship similar to that of CONV and CHY.     

P-Regular Convergence Spaces

A generalized notion of regularity is introduced which enables one to study locally compact spaces, sequential spaces, ω-regular spaces, and other diverse types of spaces as special wises of p-regular spaces.     

Approach Theory in Merotopic, Cauchy and Convergence Spaces. I

We introduce the notions of approach-merotopic structure and approach-filter merotopic structure by means of a map assigning to a collection of sets 'smallness' of members and define categories AMER and AFIL containing MER and FIL as bireflectively and bicoreflectively embedded subcategories, respectively. We show that the category AMER is a topological construct and AFIL which is a supercategory of ps-MET as well is a cartesian closed topological category bicoreflectively embedded in AMER.     

Yang-Mills模空间上的有限群作用

设Ｘ是单连通光滑闭４－流形,有限群Ｇ光滑作用于Ｘ,令ｐ：Ｅ→Ｘ是Ｘ上具有光滑Ｇ作用的ＳＵ（２）从且ｐ是一个Ｇ映射．本文研究了丛Ｅ上等模空间Ｍ＾Ｇ和商丛Ｅ’→Ｘ’上的关键空间之间的关系,并讨论了不变模空间的紧致化。     

Spectral Convergence of Quasi-One-Dimensional Spaces

We consider a family of non-compact manifolds X_ε (“graph-like manifolds”) approaching a metric graph X₀ and establish convergence results of the related natural operators, namely the (Neumann) Laplacian and the generalized Neumann (Kirchhoff) Laplacian on the metric graph. In particular, we show the norm convergence of the resolvents, spectral projections and eigenfunctions. As a consequence, the essential and the discrete spectrum converge as well. Neither the manifolds nor the metric graph need to be compact, we only need some natural uniformity assumptions. We provide examples of manifolds having spectral gaps in the essential spectrum, discrete eigenvalues in the gaps or even manifolds approaching a fractal spectrum. The convergence results will be given in a completely abstract setting dealing with operators acting in different spaces, applicable also in other geometric situations. Communicated by Claude Alain Pillet Submitted: December 21, 2005 Accepted: January 30, 2006     

Closure Operators in Convergence Spaces

We define two closure operators of some well-known topological categories and investigate the relationships between these closure operators and the one that is given in [9]. As a consequence, we characterize separation properties T ₀, T ₁, and T ₂ for these well-known categories and compare them with the ones that are given in [3] and [6]. Finally, we characterize the epimorphisms in the subcategories of these given categories. This revised version was published online in June 2006 with corrections to the Cover Date.     

Completion of Semiuniform Convergence Spaces

Semiuniform convergence spaces form a common generalization of filter spaces (including symmetric convergence spaces [and thus symmetric topological spaces] as well as Cauchy spaces) and uniform limit spaces (including uniform spaces) with many convenient properties such as cartesian closedness, hereditariness and the fact that products of quotients are quotients. Here, for each semiuniform convergence space a completion is constructed, called the simple completion. This one generalizes Császár's -completion of filter spaces. Thus, filter spaces are characterized as subspaces of convergence spaces. Furthermore, Wyler's completion of separated uniform limit spaces can be easily derived from the simple completion.     

包含度空间中的收敛性

本文引入包含度空间中的Ｄ－收敛和滤子收敛,并证明二者等价;然后给出Ｌ＾ｐ「ａ,ｂ」（１≤ｐ〈∞）空间中的又一种包含度收敛,证明其与测度收敛等价。     

Isometric Group Actions on Hilbert Spaces: Growth of Cocycles

We study growth of 1-cocycles of locally compact groups, with values in unitary representations. Discussing the existence of 1-cocycles with linear growth, we obtain the following alternative for a class of amenable groups G containing polycyclic groups and connected amenable Lie groups: either G has no quasi-isometric embedding into a Hilbert space, or G admits a proper cocompact action on some Euclidean space. On the other hand, noting that almost coboundaries (i.e. 1-cocycles approximable by bounded 1-cocycles) have sublinear growth, we discuss the converse, which turns out to hold for amenable groups with “controlled” F?lner sequences; for general amenable groups we prove the weaker result that 1-cocycles with sufficiently small growth are almost coboundaries. Besides, we show that there exist, on a-T-menable groups, proper cocycles with arbitrary small growth. Received: August 2005 Revision: October 2006 Accepted: November 2006     

直觉模糊度量空间上的半群作用

讨论在直觉模糊度量空间上的拓扑半群作用,引入诸如拓扑传递性,点传递性及点稠传递性等概念.考虑非敏感性与传递性,等度连续等动力学性质的相互关系.     

L-模糊化拓扑空间中的Moore-Smith收敛理论

This paper presents a definition of L-fuzzifying nets and the related L-fuzzifying generalized convergence spaces. The Moore-Smith convergence is established in L-fuzzifying topology. It is shown that the category of L-fuzzifying generalized convergence spaces is a cartesianclosed topological category which embeds the category of L-fuzzifying topological spaces as a reflective subcategory.     

Local Compactness in Fuzzy Convergence Spaces

Two notions of local precompactness in the realm of fuzzy convergence spaces are investigated. It is shown that the property of local precompactness possesses a “good extension.” Moreover, for each given fuzzy convergence space, there exists a coarsest locally precompact space which is finer than the original space. Continuity between fuzzy spaces is preserved between the associated locally precompact spaces. Invariance of regularity with respect to taking locally precompact modifications is discussed.     

Ultrafilter Convergence in Ordered Topological Spaces

We characterize ultrafilter convergence and ultrafilter compactness in linearly ordered and generalized ordered topological spaces. In such spaces, and for every ultrafilter D, the notions of D-compactness and of D-pseudocompactness are equivalent. Any product of initially λ-compact generalized ordered topological spaces is still initially λ-compact. On the other hand, preservation under products of certain compactness properties is independent from the usual axioms for set theory.     

Categorical Properties of Probabilistic Convergence Spaces

The purpose of this paper is to discuss some categorical properties of probabilistic convergence spaces. Its main theses are: (1) the construct P-PrTop of probabilistic pretopological spaces is the extensional topological hull of the construct FTPcs of FT-diagonal probabilistic convergence spaces for every triangular norm T; (2) the construct P-PsTop of probabilistic pseudotopological spaces is the topological universe hull of FTPcs for every triangular norm T.