Understanding Disconnectedness in Countable Metric Spaces

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Discussion Overview

The discussion revolves around the properties of disconnectedness in countable metric spaces, particularly focusing on discrete metric spaces and their connectivity based on the number of points they contain. Participants explore the implications of statements regarding the connectivity of metric spaces with varying numbers of points.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants assert that every discrete metric space with at least 2 points is totally disconnected.
  • Others argue that a countable metric space with 2 or more points is disconnected, questioning the interpretation of the statement regarding connectivity.
  • A participant seeks clarification on the equivalent statement of "no discrete metric space with more than 2 points is connected."
  • Another participant emphasizes that the statement "every discrete space with more than 2 points is disconnected" is not universally true, as a discrete space with exactly 2 points is also disconnected.
  • One participant counters that the truth of a statement regarding numbers greater than 2 does not depend on its validity for numbers less than or equal to 2, suggesting that the original statement about countable metric spaces remains valid.

Areas of Agreement / Disagreement

Participants express differing views on the validity of statements regarding the connectivity of discrete metric spaces, leading to a lack of consensus on the interpretation of these statements.

Contextual Notes

Participants highlight the importance of definitions and the implications of statements based on the number of points in a metric space, but do not resolve the underlying disagreements.

Bachelier
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We know that every discrete metric space with at least 2 points is totally disconnected.
Yet I read this:
A MS that is countable with more than 2 pts is disconnected. Is it that I'm misreading this statement. It sounds like if it has 2 or less points it is connected?
more means greater than.
 
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Well, a metric space with 2 points is disconnected. So the statement should be: a countable metric space with 2 or more points is disconnected.
 
what is the equivalent statement of:

no discrete MS with more than 2 pts is connectd?
 
Every discrete space with more than 2 points is disconnected?
 
micromass said:
Every discrete space with more than 2 points is disconnected?

Exactly, which is false. because of we have a discrete MS X with 2 pts it is also disconnected. Yet the statement asks every discrete MS with > 2 pts.
 
That doesn't make the statement false! If I say: for all numbers n greater than 2 it holds that n+0=n, then this statement is true. Whether it holds for other numbers n does not change the validity of the statement.

So the truth of the statement "every countable metric space with more than 2 points is disconnected" is independent of what happens for 2 points!
 
micromass said:
That doesn't make the statement false! If I say: for all numbers n greater than 2 it holds that n+0=n, then this statement is true. Whether it holds for other numbers n does not change the validity of the statement.

So the truth of the statement "every countable metric space with more than 2 points is disconnected" is independent of what happens for 2 points!

Makes sense. thanks
 

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