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Education > Math Undergrad > Re: topology
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Re: topology

by amu <amu786la@[EMAIL PROTECTED] > May 4, 2008 at 07:30 PM

is this proof write to above question

Let C be a connected set that is also locally path connected.  Pick any
point x in C, and let U be the set of points in C that are path connected
to x.  Thus U is a subset of C. 
Let y be a point in U.  Enclose y in an open set H in C, such that y is
path connected to all of H.  Since an arc can run from x to y to anything
in H, H is in U.  Therefore U is the union of open sets and is open,
relative to C. 

Let y be a point in C that is a limit point of U.  Put an open set H
around y such that H is path connected.  Let z be common to H and U.  Now
x connects to z connects to y, and y is in U. 

Since U contains its limit points it is closed.  thus U is both open and
closed in C.  If U is not all of C, separate U and the rest of C in open
sets.  This contradicts the fact that C is connected.  Therefore U is all
of C, and C is path connected. 

In n dimensional space, every open ball is path connected, and every open
set is locally path connected, hence every open connected set is path
connected.
 




 14 Posts in Topic:
topology
amu <amu786la@[EMAIL P  2008-05-02 20:33:18 
Re: topology
Paul Sperry <plsperry@  2008-05-03 02:20:50 
Re: topology
amu <amu786la@[EMAIL P  2008-05-02 22:54:16 
Re: topology
Paul Sperry <plsperry@  2008-05-03 04:34:09 
Re: topology
amu <amu786la@[EMAIL P  2008-05-03 23:41:53 
Re: topology
amu <amu786la@[EMAIL P  2008-05-03 23:39:27 
Re: topology
Virgil <Virgil@[EMAIL   2008-05-03 23:09:28 
topology
William Elliot <marsh@  2008-05-04 01:05:58 
Re: topology
amu <amu786la@[EMAIL P  2008-05-04 15:18:22 
Re: topology
Virgil <Virgil@[EMAIL   2008-05-04 13:32:48 
Re: topology
William Elliot <marsh@  2008-05-04 22:46:09 
Re: topology
amu <amu786la@[EMAIL P  2008-05-04 19:30:27 
Re: topology
William Elliot <marsh@  2008-05-05 01:33:43 
Re: topology
William Elliot <marsh@  2008-05-05 01:34:51 

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tan12V112 Wed Dec 3 14:53:13 CST 2008.