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Topic: looking for example of closed set that is *not* complete in a metric space
Replies: 26   Last Post: Feb 3, 2013 11:06 AM

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William Hughes

Posts: 1,786
Registered: 12/7/10
Re: looking for example of closed set that is *not* complete in a
metric space

Posted: Feb 1, 2013 5:32 PM
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On Feb 1, 11:25 pm, Tonic...@yahoo.com wrote:
> On Friday, February 1, 2013 6:37:40 PM UTC+2, Daniel J. Greenhoe wrote:
> > Let (Y,d) be a subspace of a metric space (X,d).
>
> > If (Y,d) is complete, then Y is closed with respect to d. That is,
>
> >   complete==>closed.
>
> > Alternatively, if (Y,d) is complete, then Y contains all its limit
>
> > points.
>
> > Would anyone happen to know of a counterexample for the converse? That
>
> > is, does someone know of any example that demonstrates that
>
> >    closed --> complete
>
> > is *not* true? I don't know for sure that it is not true, but I might
>
> > guess that it is not true.
>
> > Many thanks in advance,
>
> > Dan
>
> Perhaps what you want, if I understand you correctly, is within reach in a very familiar space: take the reals R with the usual, euclidean topology (or look at  R as the euclidean metric space we all know: it's the same). This is a complete space, yet the CLOSED subset [0,+oo) isn't complete...
>
> Tonio


Why is [0,+oo) not complete?


Date Subject Author
2/1/13
Read looking for example of closed set that is *not* complete in a metric space
Achimota
2/1/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Paul
2/1/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Paul
2/1/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
fom
2/1/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
fom
2/2/13
Read Re: looking for example of closed set that is *not* complete in a metric space
Shmuel (Seymour J.) Metz
2/3/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
fom
2/3/13
Read Re: looking for example of closed set that is *not* complete in a metric space
Shmuel (Seymour J.) Metz
2/2/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Achimota
2/2/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Butch Malahide
2/2/13
Read Re: looking for example of closed set that is *not* complete in a metric space
quasi
2/2/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Butch Malahide
2/2/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Achimota
2/2/13
Read Re: looking for example of closed set that is *not* complete in a metric space
quasi
2/3/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Achimota
2/3/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Paul
2/3/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Achimota
2/1/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Butch Malahide
2/1/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
J. Antonio Perez M.
2/1/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
William Hughes
2/2/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
J. Antonio Perez M.
2/1/13
Read Re: looking for example of closed set that is *not* complete in a
metric space
Butch Malahide
2/1/13
Read closed but not complete
William Elliot
2/2/13
Read Re: closed but not complete
Butch Malahide
2/2/13
Read Re: closed but not complete
William Elliot
2/2/13
Read Re: closed but not complete
Butch Malahide
2/2/13
Read Re: closed but not complete
Shmuel (Seymour J.) Metz

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