Movability and limits of polyhedra

We define a metric d(S), called the shape metric, on the hyperspace 2X of all non-empty compact subsets of a metric space X. Using it we prove that a compactum X in the Hilbert cube is movable if and only if X is the limit of a sequence of polyhedra in the shape metric. This fact is applied to show...

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Bibliographic Details
Authors: Fernández Laguna, Víctor, Alonso Morón, Manuel, Nhu, Nguyen Tho, Rodríguez Sanjurjo, José Manuel
Format: article
Publication Date:1993
Country:España
Institution:Universidad Complutense de Madrid (UCM)
Repository:Docta Complutense
Language:English
OAI Identifier:oai:docta.ucm.es:20.500.14352/57334
Online Access:https://hdl.handle.net/20.500.14352/57334
Access Level:Open access
Keyword:151.143
515.164.251
515.124
Shape metric
Polyhedra
Metric space
Topología
1210 Topología
Description
Summary:We define a metric d(S), called the shape metric, on the hyperspace 2X of all non-empty compact subsets of a metric space X. Using it we prove that a compactum X in the Hilbert cube is movable if and only if X is the limit of a sequence of polyhedra in the shape metric. This fact is applied to show that the hyperspace (2R2, d(S)) is separable. On the other hand, we give an example showing that 2R2 is not separable in the fundamental metric introduced by Borsuk.