Show that a homeomorphism preserves uniform continuity

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Homework Help Overview

The problem involves metric spaces and the properties of functions between them, specifically focusing on uniform continuity in the context of homeomorphisms. The original poster attempts to show that if a composition of functions is uniformly continuous, then one of the functions must also be uniformly continuous, leveraging the properties of compactness and continuity.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the implications of compactness on the continuity of functions, questioning the relationship between the compactness of the domain and the uniform continuity of the functions involved. There is an exploration of the properties of continuous functions on compact domains and how they relate to the uniform continuity of the function f.

Discussion Status

Some participants have provided insights into the properties of continuous functions on compact domains, suggesting that these properties may lead to conclusions about uniform continuity. The original poster expresses a moment of realization after receiving guidance, indicating a productive direction in the discussion.

Contextual Notes

There is a noted uncertainty regarding the compactness of the domain of function f, which is central to the discussion of uniform continuity. The constraints of the problem and the definitions being used are under examination.

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Homework Statement



(X,d1),(Y,d2) and (Z,d3) are metric spaces, Y is compact,
g(y) is a continuous function that maps Y->Z with a continuous inverse
If f(x) is a function that maps X->Y, and h(x) maps X->Z such that h(x)=g(f(x))
Show that if h is uniformly continuous, f is uniformly continuous

Homework Equations



if h is continuous, f is continuous

The Attempt at a Solution



I proved that f is continuous when h is continuous.
I also know that g is a homeomorphism, which preserves pretty much everything.
and that f(x)=g^(-1)(h(x)) so I just need to show that the homeomorphism preserves the uniform continuity.
 
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What do you know about continuous functions with compact domain?
 
THey have a compact range. But I don't know that f's domain is compact, only that it's range is...
 
g has a compact domain.
 
I know Y is compact, and so g(Y) is compact.
h(X) c g(Y), so h is bounded. Also, because the range of f is compact, f is bounded.
I qualitatively know that uniform continuity means that the function is not allowed to get infinitely steep, and that a continuous, bounded function obviously can't be infinitely steep, therefore it should be uniformly continuous, but I'm not sure how to say it mathematically.
 
Can you show that a continuous function on a compact domain is uniform continuous?
 
Ooooh...
Thanks. I've got it now.
 

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