topology (point-set topology, point-free topology)
see also differential topology, algebraic topology, functional analysis and topological homotopy theory
Basic concepts
fiber space, space attachment
Extra stuff, structure, properties
Kolmogorov space, Hausdorff space, regular space, normal space
sequentially compact, countably compact, locally compact, sigma-compact, paracompact, countably paracompact, strongly compact
Examples
Basic statements
closed subspaces of compact Hausdorff spaces are equivalently compact subspaces
open subspaces of compact Hausdorff spaces are locally compact
compact spaces equivalently have converging subnet of every net
continuous metric space valued function on compact metric space is uniformly continuous
paracompact Hausdorff spaces equivalently admit subordinate partitions of unity
injective proper maps to locally compact spaces are equivalently the closed embeddings
locally compact and second-countable spaces are sigma-compact
Theorems
Analysis Theorems
A stacked cover is a cover of a topological space which is indexed by a cover of another topological space, such that the product cover is a cover of the product space.
Let be topological spaces and a numerable cover of . Then a cover of the product space is called a stacked cover of over – denoted – , if there exists a function – called the stacking function – which assignes to each set a cover of , such that consists of all the sets with .
A stacked cover is itself a numerable cover.
In this section we let the standard interval and consider properties of stacked covers of spaces of the form .
For a topological space and a numerable cover of there exists a refinement of to a stacked cover of of the form
Section A.2.17 of
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