Proving Closure of T in B[0,1] Set V

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Discussion Overview

The discussion revolves around proving that a specific set, denoted as V, is closed within the metric space B[0,1]. Participants explore the definitions and properties of B[0,1], the nature of the set V, and the implications of using complements and evaluation maps in the proof process.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Post 1 raises a question about how to find the complement of the set V and expresses confusion regarding the definitions of open sets in this context.
  • Post 2 questions the nature of B[0,1], asking if it refers to continuous functions from [0,1] to R and inquires about the metric used.
  • Post 3 provides a clarification that B[0,1] could represent either continuous functions or bounded functions and outlines a potential approach to proving the closure of V using the evaluation map and properties of closed sets in R.
  • Post 5 suggests an alternative method of proving the closure of V by considering the complement and using open or closed balls, reaffirming the characterization of B[0,1] as the set of bounded functions.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the definitions and properties of B[0,1] and the set V. There is no consensus on the best approach to proving the closure of V, with multiple competing views and methods being proposed.

Contextual Notes

There are limitations in the discussion regarding the assumptions about the nature of B[0,1] and the specific properties of the functions involved. The mathematical steps and definitions are not fully resolved, leading to ambiguity in the proof process.

Who May Find This Useful

This discussion may be useful for individuals interested in functional analysis, topology, or those studying properties of metric spaces and closed sets.

Ed Quanta
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Let T be an element of B[0,1] be the set V=[B[0,1];f(1)=2]. Prove that T is closed (in metric space B[0,1]).

I am not sure if it is obvious since I am new to this stuff but B[0,1] is an open ball I believe.

My question is how do I find the complement of V. If I could define B/T then I am hoping it will follow easily from the definitions of open set that this is an open set and my proof will be complete. Is B/T=[B[0,1]; f(1)>2 V f(1)<2]? Very confused.
 
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What is B[0,1], the set of functions on [0,1] into R? Are they continuous? What is the metric?
 
standard stuff would be something like this:

1) B[0,1] is the set of continuous functions from [0,1] to the reals

or maybe because there is a B there, it is just bounded functions.

2) the topology on B[0,1] is given by say the sup norm, i.e. the distance from f to g is the furthest apart any two values f(t), g(t) ever get for t in [0,1].
3) then prove the evaluation map taking f to f(1) is continuous.

4) then the inverse image of 2 under the evaluation map is clsoed since 2 is closed in R.
 
Thanks a lot mathwonk
 
What if I were to try to solve this by taking the complement of V and using open or closed balls? Is there any way to prove it this way? B[0,1] is the set of bounded functions by the way.
 

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