On Mon, 12 Sep 2005, Brad Knowles wrote:
> Date: Mon, 12 Sep 2005 12:26:46 +0200
> From: Brad Knowles <[EMAIL PROTECTED]>
> To: [email protected]
> Subject: Re: [time] Nearby servers
> Sender: [EMAIL PROTECTED]
>
> At 10:16 AM +0200 2005-09-12, Henk P. Penning wrote:
>
> > Please read again ; I asked if it is true that
> >
> > A is close to B -->IMPLIES--> B is close to A
> >
> > If it is true, the config file can be half as big ; thats all.
>
> I understood that, and I gave a counter-example. If you go to
> the CIA World Factbook and pull up a page on a given country, you'll
> find a list of border countries specified. Try doing a full listing,
> and I think you'll find that the matrix is relatively sparse. All
> sorts of countries may be directly bordering other countries, but
> that doesn't necessarily mean that any of those border countries are
> necessarily close to any of the other border countries.
>
> If that were the case, then all of Europe would be filled with
> points where four or more countries touch or come very close
> together, and that's just not what happens.
Sigh ; please read again ; That is not what I wrote or otherwise
implied. Your remarks are entirely beside the point.
One more time :
definition : 'geographically close' means 'sharing a border'
Relation 'geographically close' is by definition symmetric :
if region A shares a border with B, then B shares a border with A.
The question I asked was
If region A is (networkwise) close to region B, is it true
that region B is (networkwise) close to region A ?
If that is true (in most cases) the 'A close to B' relation is
(mostly) symmetric and you have to specify only half the relation:
You write
a => b c d
and it implies
b => a
c => a
d => a
Ask wrote about specifying the 'A close to B' relation and I made
a suggestion (use symmetry) for the spec format. That is all.
> Brad Knowles, <[EMAIL PROTECTED]>
HPP
---------------------------------------------------------------- _
Henk P. Penning, Computer Systems Group R Uithof CGN-A232 _/ \_
Dept of Computer Science, Utrecht University T +31 30 253 4106 / \_/ \
Padualaan 14, 3584CH Utrecht, the Netherlands F +31 30 251 3791 \_/ \_/
http://www.cs.uu.nl/staff/henkp.html M [EMAIL PROTECTED] \_/
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