Is a Metric Space with Infinite Distance Totally Bounded?

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SUMMARY

A metric space consisting of two points, X={a,∞}, is not totally bounded due to the infinite distance d(a,∞)=∞. The discussion highlights that while totally bounded implies bounded, the assumption of finite distances is crucial in this context. The proof referenced from UCLA's resources assumes finite distances between points, which is a fundamental aspect of metric space definitions. Therefore, the metric space X={a,∞} contradicts the property of total boundedness.

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johnqwertyful
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It seems strange, but would a metric space consisting of two points, X={a,∞} be totally bounded, but not bounded? because d(a,∞)=∞. But for all ε>0, X=B(ε,a)UB(ε,∞).

It's been proven that totally bounded→bounded, so this is wrong. Why?
 
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johnqwertyful said:
So if we assume that the distance between every two points is finite

This "assumption" is incorporated into the definition of metrics.
 
the axioms for a metric space state that for any two points in the metric space, their distance is a real (and finite) number.
 

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