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Anglický jazyk
Extension Topology
Autor: Frederic P. Miller
Let X be a topological space and P a set disjoint from X. Consider in X ¿ P the topology whose open sets are of the form: A ¿ Q, where A is an open set of X and Q is a subset of P. Note that the closed sets of X ¿ P are of the form: B ¿ Q, where B is... Viac o knihe
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O knihe
Let X be a topological space and P a set disjoint from X. Consider in X ¿ P the topology whose open sets are of the form: A ¿ Q, where A is an open set of X and Q is a subset of P. Note that the closed sets of X ¿ P are of the form: B ¿ Q, where B is a closed set of X and Q is a subset of P. For these reasons this topology is called the extension topology of X plus P, with which one extends to X ¿ P the open and the closed sets of X. Note that the subspace topology of X as a subset of X ¿ P is the original topology of X, while the subspace topology of P as a subset of X ¿ P is the discrete topology. Being Y a topological space and R a subset of Y, one might ask whether the extension topology of Y - R plus R is the same as the original topology of Y, and the answer is in general no. Note the similitude of this extension topology construction and the Alexandroff one-point compactification, in which case, having a topological space X which one wishes to compactify by adding a point 8 in infinity, one considers the closed sets of X ¿ {8} to be the sets of the form: K, where K is a closed compact set of X, or B ¿ {8}, where B is a closed set of X.
- Vydavateľstvo: OmniScriptum
- Rok vydania: 2026
- Formát: Paperback
- Rozmer: 220 x 150 mm
- Jazyk: Anglický jazyk
- ISBN: 9786130618384
