Difference between revisions of "Equivalent statements to compactness of a metric space/Statement"

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(Created page with "<noinclude> ==Statement of theorem== </noinclude> Given a metric space {{M|(X,d)}}, the following are equivalent{{rITTGG}}<ref group="Note">To say statements are equivalen...")
 
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==Statement of theorem==
 
==Statement of theorem==
 
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Given a [[metric space]] {{M|(X,d)}}, the following are equivalent{{rITTGG}}<ref group="Note">To say statements are equivalent means we have one {{M|\iff}} one of the other(s)</ref>:
 
Given a [[metric space]] {{M|(X,d)}}, the following are equivalent{{rITTGG}}<ref group="Note">To say statements are equivalent means we have one {{M|\iff}} one of the other(s)</ref>:
 
# {{M|X}} is [[compact]]
 
# {{M|X}} is [[compact]]
# Every [[sequence]] in {{M|X}} has a [[subsequence]] that [[converges]] (has a ''convergent subsequence'')
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# Every [[sequence]] in {{M|X}} has a [[subsequence]] that [[convergent (sequence)|converges]] ({{AKA}}: having a ''convergent subsequence'')
# {{M|X}} is [[totally bounded]] and [[complete metric space|complete]]
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# {{M|X}} is [[totally bounded]] and [[complete metric space|complete]]<!--
 
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==Notes==
 
==Notes==
 
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Latest revision as of 11:39, 27 May 2016

Attention people coming in from search engines: this is a sub-page, you want Equivalent statements to compactness of a metric space

Statement of theorem

Given a metric space [ilmath](X,d)[/ilmath], the following are equivalent[1][Note 1]:

  1. [ilmath]X[/ilmath] is compact
  2. Every sequence in [ilmath]X[/ilmath] has a subsequence that converges (AKA: having a convergent subsequence)
  3. [ilmath]X[/ilmath] is totally bounded and complete

Notes

  1. To say statements are equivalent means we have one [ilmath]\iff[/ilmath] one of the other(s)

References

  1. Introduction to Topology - Theodore W. Gamelin & Robert Everist Greene