Metric spaces and convergent sequences

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SUMMARY

The discussion centers on proving that if a sequence of distinct elements {xi} in a metric space converges to a limit x, and there exists a one-to-one map f from the set of {xi} into itself, then the sequence f(xi) also converges to x. The key points include the use of the definition of convergence, the properties of one-to-one functions, and the implications of distinct elements in the sequence. The participants explore the mathematical expressions needed to demonstrate that for every ε>0, there exists an n0 such that for all i≥n0, the distance d(f(xi), x) is less than ε.

PREREQUISITES
  • Understanding of metric spaces and convergence
  • Familiarity with one-to-one functions and their properties
  • Knowledge of distance functions and ε-δ definitions in analysis
  • Ability to manipulate sequences and limits in mathematical proofs
NEXT STEPS
  • Study the properties of metric spaces, focusing on convergence and continuity
  • Learn about the implications of one-to-one mappings in mathematical analysis
  • Explore the ε-δ definition of limits in greater detail
  • Investigate examples of convergent sequences and their transformations under various functions
USEFUL FOR

Mathematics students, particularly those studying real analysis or topology, as well as educators looking to deepen their understanding of convergence in metric spaces.

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Homework Statement


let {xi} be a sequence of distinct elements in a metric space, and suppose that xi→x. Let f be a one-to-one map of the set of xis into itself. prove that f(xi)→x

Homework Equations


by convergence of xi, i know that for all ε>0, there exists some n0 such that if i≥n0, then d(xi,x)<ε.
by one to one, i know that if f(x)=f(y), then x=y.
xis are distinct (which implies that there are an infinite number of points?)
f(xi) ⊆ {xi} (with this and one to one, does that imply the function is onto? i think yes, since the cardinality of the two sets are equal, but I'm not sure this will help me)

i want to show: for all ε>0, there exists some n0 such that if i≥n0, then d(f(xi),x)<ε.


The Attempt at a Solution


so I've been staring at this problem for hours, not getting farther than stating my assumptions. I'm having a hard time even convincing myself that it's true, which is usually my first step. I'm thinking that since there are an infinite amount of points, then no matter what function i have, any mapping will "fill up" the earlier holes, leaving me with a remaining series that lies in any epsilon neighborhood, but I'm having trouble expressing that mathematically, and I'm not even sure if it's true. i got my hopes up by trying use a contradiction and assuming the negation of what I'm trying to show, thinking that since f(xa)=xb for some a, b in N, but all that does is show that there is a sequence, not one necessarily related by the i's (am i making sense? i mean i need the f(xi) to converge, not create a new sequence by reordering my f(xi) such that it converges), and we already knew that sequence exists.
 
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If d(xi,x)<ε for all i≥n0 then the i values where d(xi,x)>=ε are finite in number, since i<=n0. So those f(i) values must have maximum, yes? Call it n1. So for i>n1 what about d(x_f(i),x)?
 
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