Continuity in Metric Spaces: Proving the Convergence of a Sequence

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Homework Help Overview

The discussion revolves around proving the convergence of a sequence (f(x_n)) in the reals, given that (x_n) converges to a point x in a metric space (E,d). The problem touches on the concept of continuity in metric spaces.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the implications of continuity for the function f and its effect on the convergence of the sequence (f(x_n)). There is a discussion about the necessity of continuity for the proof and examples are provided to illustrate potential pitfalls when f is not continuous.

Discussion Status

The discussion is ongoing, with participants questioning the assumptions regarding the continuity of the function f. Some have pointed out that without continuity, the original poster's assertion may not hold true. There is an exploration of different scenarios and examples to clarify these points.

Contextual Notes

It is noted that the problem does not specify whether the function f is continuous, which is central to the discussion. This lack of information is causing uncertainty in the participants' reasoning.

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Homework Statement


Show that if (x_{n}) is a sequence in a metric space (E,d) which converges to some x\inE, then (f(x_{n})) is a convergent sequence in the reals (for its usual metric).


Homework Equations


Since (x_{n}) converges to x, for all ε>0, there exists N such that for all n\geqN, d(x_{n},x)<ε.
So |x-x_{n}|<ε


The Attempt at a Solution


I understand that this will prove continuity, but I'm not sure how to get from d(x_{n},x)<ε to what we want: d(f(x_{n}_,f(x))<ε
 
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If f is continuous then from d(x,x_n)\rightarrow 0 you can deduce d(f(x_n),f(x))\rightarrow 0 (by definition).

Anyway for f general this might not be the case, take f(x)=1/x, x_n =1/n. x_n ->0 but f(0) is not defined.
 
We aren't given that f is continuous, which is why I'm stuck.
 
gotmilk04 said:
We aren't given that f is continuous, which is why I'm stuck.

If f is not continuous, then the statement in the OP is false.
 

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