منابع مشابه
Entourages, Covers and Localic Groups
Due to the nature of product in the category of locales, the entourage uniformities in the point-free context only mimic the classical Weil approach while the cover (Tukey type) ones can be viewed as an immediate extension. Nevertheless the resulting categories are concretely isomorphic. We present a transparent construction of this isomorphism, and apply it to the natural uniformities of local...
متن کاملNotes on Entourages and Localic Groups
The relation between the cover (Tukey type) uniformities and the entourage (Weil type) ones, in the point-free context, is studied and a transparent translation is presented. In particular the natural uniformities on localic groups are discussed, and the uniformity of localic group homomorphisms is proved.
متن کاملFractional Coverings, Greedy Coverings, and Rectifier Networks
A rectifier network is a directed acyclic graph with distinguished sources and sinks; it is said to compute a Boolean matrix M that has a 1 in the entry (i, j) iff there is a path from the jth source to the ith sink. The smallest number of edges in a rectifier network that computes M is a classic complexity measure on matrices, which has been studied for more than half a century. We explore two...
متن کاملOn proximities generated by countable families of entourages
It is shown that any proximity that is generated by a countable family of entourages is sequential. Metrization theorems for proximities are derived.
متن کاملOn category of co-coverings
In this article, we introduce the concept of co-covering which is the dual of covering concept. Then, we prove several theorems being similar to the theorems that have been de-veloped for the covering concept. For example, we provide the lifting criterion for co-coverings of a topological space X, which helps us to classify them by subgroups of the group of all homeomorphisms of X.
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ژورنال
عنوان ژورنال: Topology and its Applications
سال: 1998
ISSN: 0166-8641
DOI: 10.1016/s0166-8641(97)00054-0