弱空间式Locale

空间式locale范畴SLoc是locale范畴Loc的余反射满子范畴,但对locale乘积不封闭．本文引入弱空间式locale,证明弱空间式locale范畴WSloc为范畴Loc的余反射满子范畴,且对locale秉积封闭．还证明了一个locale A是空间式的当且仅当它的枝映射localeN(A)是弱空间式的;一个空问式locale的每一个子locale都是空间式的当且仅当它的每一个子locale是弱空间式的．最后,证明了弱空间式性在定向函子下保持不变．     

Locale的仿紧完全正则反射

1972年, Isbell利用locale中由正规覆盖构成的一致结构的完备化, 证明了仿紧完全正则locale范畴是locale范畴的满反射子范畴. 本文通过在locale的补零元理想格上做核映射的方法, 给出locale的仿紧完全正则反射的明确构造, 并证明locale的仿紧完全正则反射是locale的 Stone-Čech紧化的子locale.     

Locale的弱拓扑表达

本文引入了弱拓扑空间的概念,证明了locale范畴与弱拓扑空间范畴的关系类似于拓扑空间范畴与locale范畴的关系。locale范畴严格包含于弱拓扑空间范畴并且与Sober的弱拓扑空间范畴等价。     

有向图的基本群和覆盖（英文）

本文基于范畴理论,主要研究了有向图和其对应的无向图(简称为图)在不同同伦等价意义下基本群之间的关系,证明了覆盖映射所诱导的覆盖图和底图的基本群之间的同态是单同态.设G是连通有向图,G是G的万有覆盖,覆盖映射为p.我们证明了G的覆盖转化群D(G,p)同构于G在C-同伦意义下的基本群.     

locale范畴中的逆极限

给出locale范畴中逆极限结构的明确描述 .借助于引入的一种新的极限形式———集体拉回 ,详细讨论了逆极限的性质 ,特别地 ,不用选择公理证明了locale形式的Steenrod定理 ,并且证明了紧空间式locale的逆极限一般不是空间式的 .作为在拓扑空间范畴中的应用 ,改进了经典拓扑学中的Steenrod定理     

单纯广群的准层和同伦纤维

显示了在设置C上的单纯广群的准层的范畴是个封闭模型范畴.证明了在一个单纯广群的准层G上的单纯函子X是局部弱等价于同伦纤维.     

关于链同伦前伸的注记

首先,本文在链复形和链映射范畴d中证明了各种同伦扩张性质(HEP,WHEP,RWHEP与VWHEP)是等价的.这不同于拓扑空间和连续映射范畴Top.其次,在范踌d中也有Puppe序列,本文证明了约化奇异链函子保持Puppe序列的右正合性.最后,与范畴Top相类似,在链同伦前伸方块中一个链同伦等价诱导出另一个链同伦等价.     

关于链同伦前伸的注记

首先,本文在链复形和链映射范畴d中证明了各种同伦扩张性质(HEP,WHEP,RWHEP与VWHEP)是等价的.这不同于拓扑空间和连续映射范畴Top.其次,在范踌d中也有Puppe序列,本文证明了约化奇异链函子保持Puppe序列的右正合性.最后,与范畴Top相类似,在链同伦前伸方块中一个链同伦等价诱导出另一个链同伦等价.     

相对于子范畴的同伦分解的存在性

本文证明了在相对于子范畴的情形下上有界复形的同伦分解的存在性,推广了经典的复形的同伦分解,是使得相对导出范畴具有可操作性的基础.进一步,证明了在R-模范畴和相对于特殊子范畴的情形下,任意无界复形的同伦分解的存在性.最后,建立了同伦范畴和相对导出范畴的(余)局部化序列.     

涉及迹同伦范畴的几对伴随函子

Ｋ．Ａ．Ｈａｒｄｉｅ与Ｋ．Ｈ．Ｋａｍｐｓ研究过固定空间Ｂ上的迹同伦范畴（［１］）．他们引进了两对伴随函子ＰＢ┤ＮＢ与ｍ┤ｍ，此处ｍ：ＡＢ是固定映射，ＰＢ：ＨＢＨＢ与ｍ：ＨＡＨＢ是函子．我们在［２］中引进了分裂的范畴纤维化Ｌ：ＨｂＨＢ，并且证明了Ｌ┤Ｊ，Ｊ┤Ｌ．本文首先将ＰＢ┤ＮＢ推广到ＰＢｂ┤ＮＢｂ＃，其中ｂ：ＢＢ是任一固定映射，并且我们还得到涉及迹同伦范畴Ｈｂ与Ｈｂ的两对伴随函子，此处Ｈｂ是Ｈｂ的对偶．特别，Ｎｂ┤Ｐｂ不同于ＰＢ┤ＮＢ．     

Locale范畴中的零维性

本文讨论ｌｏｃａｌｅ的零维性质，主要结果有：（１）给出ｌｏｃａｌｅＡ的核映射（ｎｕｃｌｅｕｓ）构成的ｌｏｃａｌｅＮ（Ａ）中上确界的点式刻划，并得到了Ｎ（Ａ）的紧性与Ａ的紧性之间的关系；（２）给出零维ｌｏｃａｌｅ与ｃｏｈｅｒｅｎｔｌｏｃａｌｅ之间的关系，以及零维ｌｏｃａｌｅ的紧零维反射；（３）给出零维ｌｏｃａｌｅ范畴在ｌｏｃａｌｅ范畴中的刻划．     

Separating families of locale maps and localic embeddings

We establish the notion of a separating family of locale maps, which is the localic analogue of the topological concept of separating points from closed sets by continuous maps. We then present a localic version of the topological embedding (or diagonal) theorem. Applications to arbitrary locales, zero-dimensional locales, and completely regular locales are given. Using the axiom of choice, we are able to control the number of factors of the target localic products so that it does not exceed the weight of the embeddable locale. Apart from the proofs of results involving the weights of locales, the remaining proofs are valid in topos logic.     

Localization,completion and detecting equivariant maps on skeletons

In the category of equivariant spaces with base point, we prove the injectivity of the induced map between homotopy sets under some conditions. We study some relations between the localization and the completion. By using these results, we characterize continuous maps which are homotopic on skeletons, and obtain a generalization of the theory of phantom maps.     

An algebraic approach to chaos

The aim of this paper is to study chaotic actions on objects other than metric spaces, e.g. locales and commutative rings. To do so, point-free versions of topologically transitivity and the density of periodic points are obtained for actions on a locale, and then generalized to a category which includes the desired objects of study.Presented at the European Colloquium of Category Theory, Tours, France, 25–31 July 1994.     

Embedding locales and formal topologies into positive topologies

A positive topology is a set equipped with two particular relations between elements and subsets of that set: a convergent cover relation and a positivity relation. A set equipped with a convergent cover relation is a predicative counterpart of a locale, where the given set plays the role of a set of generators, typically a base, and the cover encodes the relations between generators. A positivity relation enriches the structure of a locale; among other things, it is a tool to study some particular subobjects, namely the overt weakly closed sublocales. We relate the category of locales to that of positive topologies and we show that the former is a reflective subcategory of the latter. We then generalize such a result to the (opposite of the) category of suplattices, which we present by means of (not necessarily convergent) cover relations. Finally, we show that the category of positive topologies also generalizes that of formal topologies, that is, overt locales.     

Isocompactness in the Category of Locales

We study isocompactness in Loc defined, exactly as in Top, by requiring that every countably compact closed sublocale be compact. This is a genuine extension of the same-named topological concept since every Boolean (or, even more emphatically, every paracompact) locale is isocompact. A slightly stronger variant is defined by decreeing that the closure of every complemented countably compact sublocale be compact. Dropping the adjective “complemented” yields a formally even stronger property, which we show to be preserved by finite products. Metrizable locales (or, more generally, perfectly normal locales) do not distinguish between the three variants of isocompactness. Each of the stronger variants of isocompactness travels across a proper map of locales, and in the opposite direction if the map is a surjection in Loc.     

Directed inverse limits of spatial locales

In this note we consider spatiality of directed inverse limits of spatial locales. We give an example which shows that directed inverse limits of compact spatial locales are not necessarily spatial. This answers a question posed by John Isbell. We also give a condition which, if satisfied by the maps of a directed inverse system, implies that taking limits preserves local compactness and hence produces spatial locales.

     

Closed Simplicial Model Structures for Exterior and Proper Homotopy Theory

The notion of exterior space consists of a topological space together with a certain nonempty family of open subsets that is thought of as a system of open neighbourhoods at infinity while an exterior map is a continuous map which is continuous at infinity. The category of spaces and proper maps is a subcategory of the category of exterior spaces.In this paper we show that the category of exterior spaces has a family of closed simplicial model structures, in the sense of Quillen, depending on a pair {T,T} of suitable exterior spaces. For this goal, for a given exterior space T, we construct the exterior T-homotopy groups of an exterior space under T. Using different spaces T we have as particular cases the main proper homotopy groups: the Brown–Grossman, erin–Steenrod, p-cylindrical, Baues–Quintero and Farrell–Taylor–Wagoner groups, as well as the standard (Hurewicz) homotopy groups.The existence of this model structure in the category of exterior spaces has interesting applications. For instance, using different pairs {T,T}, it is possible to study the standard homotopy type, the homotopy type at infinity and the global proper homotopy type.     

Weakly Hyperbolic Actions of Kazhdan Groups on Tori

We study the ergodic and rigidity properties of weakly hyperbolic actions. First, we establish ergodicity for C² volume preserving weakly hyperbolic group actions on closed manifolds. For the integral action generated by a single Anosov diffeomorphism this theorem is classical and originally due to Anosov. Motivated by the Franks/Manning classification of Anosov diffeomorphisms on tori, we restrict our attention to weakly hyperbolic actions on the torus. When the acting group is a lattice subgroup of a semisimple Lie group with no compact factors and all (almost) simple factors of real rank at least two, we show that weak hyperbolicity in the original action implies weak hyperbolicity for the induced action on the fundamental group. As a corollary, we obtain that any such action on the torus is continuously semiconjugate to the affine action coming from the fundamental group via a map unique in the homotopy class of the identity. Under the additional assumption that some partially hyperbolic group element has quasi-isometrically embedded lifts of unstable leaves to the universal cover, we obtain a conjugacy, resulting in a continuous classification for these actions. Partially funded by VIGRE grant DMS-9977371 Received: January 2005 Revision: August 2005 Accepted: September 2005