finite subcover
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Locally finite collection — In the mathematical field of topology, local finiteness is a property of collections of subsets of a topological space. It is fundamental in the study of paracompactness and topological dimension. A collection of subsets of a topological space X… … Wikipedia
Heine–Borel theorem — In the topology of metric spaces the Heine–Borel theorem, named after Eduard Heine and Émile Borel, states:For a subset S of Euclidean space R n , the following two statements are equivalent: * S is closed and bounded *every open cover of S has a … Wikipedia
Compact space — Compactness redirects here. For the concept in first order logic, see compactness theorem. In mathematics, specifically general topology and metric topology, a compact space is an abstract mathematical space whose topology has the compactness… … Wikipedia
Subbase — In highway engineering, subbase is a layer between subgrade and the base course.In topology, a subbase (or subbasis) for a topological space X with topology T is a subcollection B of T which generates T , in the sense that T is the smallest… … Wikipedia
Glossary of topology — This is a glossary of some terms used in the branch of mathematics known as topology. Although there is no absolute distinction between different areas of topology, the focus here is on general topology. The following definitions are also… … Wikipedia
Cover (topology) — In mathematics, a cover of a set X is a collection of sets whose union contains X as a subset. Formally, if is an indexed family of sets Uα, then C is a cover of X if Contents 1 Cover in t … Wikipedia
Paracompact space — In mathematics, a paracompact space is a topological space in which every open cover admits a locally finite open refinement. Paracompact spaces are sometimes also required to be Hausdorff. Paracompact spaces were introduced by Dieudonné (1944).… … Wikipedia
Tube lemma — In mathematics, particularly topology, the tube lemma is a useful tool in order to prove that the finite product of compact spaces is compact. It is in general, a concept of point set topology. Tube lemmaBefore giving the lemma, we note the… … Wikipedia
Topological property — In topology and related areas of mathematics a topological property or topological invariant is a property of a topological space which is invariant under homeomorphisms. That is, a property of spaces is a topological property if whenever a space … Wikipedia
Lindelöf space — In mathematics, a Lindelöf space is a topological space in which every open cover has a countable subcover. A Lindelöf space is a weakening of the more commonly used notion of compactness , which requires the existence of a finite subcover.A… … Wikipedia
König's lemma — or König s infinity lemma is a theorem in graph theory due to Dénes Kőnig (1936). It gives a sufficient condition for an infinite graph to have an infinitely long path. The computability aspects of this theorem have been thoroughly investigated… … Wikipedia