Complete metric spaces
A metric space is complete when every Cauchy sequence has a limit in that space.
Key knowledge
A metric space is complete when every Cauchy sequence has a limit in that space. Closed subsets of complete spaces are complete; compact metric spaces are complete, while completeness alone does not imply compactness.
Conditions and scope
- Completeness depends on the metric.
- An interval with a missing endpoint can contain a Cauchy sequence whose limit lies outside it.
Sources · 1
References
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Evidence and review
Definition 7.4.3, Proposition 7.4.6, Exercise 7.4.6 and noncompact R example 7.4.8; general compact-complete exercise verified via convergent subsequence and Cauchy property.
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- University core expansion