Are These Metric Spaces Topologically Equivalent but Not Both Complete?

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SUMMARY

The discussion centers on the identification of two metric spaces, specifically the open unit disc and R², which are topologically equivalent yet exhibit a key difference in completeness. The open unit disc is not complete as it contains Cauchy sequences that converge to limits outside the disc, while R² is complete. This example effectively demonstrates the concept of topological equivalence without mutual completeness.

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Homework Statement


Give an example of two metric spaces (X1, d1) and (X2, d2) which are topologically equivalent and for which (X1, d1) is complete and (X2, d2) is not.


2. The attempt at a solution
The open unit disc and R2. They are homeomorphic, but there are Cauchy sequences in the disc which will converge to limits outside of the disc, so it's not complete.
 
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I can't argue with your reasoning.
 
Thanks - I was pretty sure, but wanted to check.
 

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