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Why "separable"? What's being separated? Is it something like, e.g., a rational number separates any two real numbers? [[User:BenFrantzDale|—Ben FrantzDale]] 23:42, 25 October 2006 (UTC)
Why "separable"? What's being separated? Is it something like, e.g., a rational number separates any two real numbers? [[User:BenFrantzDale|—Ben FrantzDale]] 23:42, 25 October 2006 (UTC)

These two properties are a bit unclear:

* Every second-countable space is separable.
* A metric space is separable if and only if it is second-countable and if and only if it is Lindelöf.

Clearly a MS is a space so if separable iff second countable; so should the second one not be

In a Metric space the following are equivalent:
-- space 2nd countable
-- space separable
-- space Lindelof

This is not an edit as I would need to check first in Kelley.

Revision as of 11:23, 18 April 2007

This needs to be merged with separable space. Charles Matthews

(This has been done.)


Hi Fropuff,

I do not think your condensing made the article clearer. You removed my introduction sentence where I tried to give an intuitive explanation for the laymen (or not topologist) in terms of approximation. Furthermore although the ==Definition== section was quite short it was nonetheless useful for the reader as he could immediatly jump the the definition of the concept without scanning the whole article.

Your other edits , especially on the properties I added, are an improvement and made the article clearer.MathMartin 12:21, 6 Mar 2005 (UTC)

Hmm, User:Charles Matthews's edits made my points above somewhat moot. I still would like to see the definition separated out into a ==Definition== section but now I can live with the page. MathMartin 13:20, 6 Mar 2005 (UTC)

Sorry, I hadn't really looked at what changes you'd made before I made mine. In most cases I would agree with you regarding the definition section, however, in this case I think the definition is short enough and clear enough that it doesn't hurt to include it in the first sentence. -- Fropuff 15:36, 2005 Mar 6 (UTC)

Name

Why "separable"? What's being separated? Is it something like, e.g., a rational number separates any two real numbers? —Ben FrantzDale 23:42, 25 October 2006 (UTC)[reply]

These two properties are a bit unclear:

  • Every second-countable space is separable.
  • A metric space is separable if and only if it is second-countable and if and only if it is Lindelöf.

Clearly a MS is a space so if separable iff second countable; so should the second one not be

In a Metric space the following are equivalent:

-- space 2nd countable
-- space separable
-- space Lindelof

This is not an edit as I would need to check first in Kelley.