Re: Canonical DB

From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Sat, 24 Jun 2006 21:34:14 +0200
Message-ID: <449d933f$0$31641$e4fe514c@news.xs4all.nl>

Dmitry A. Kazakov wrote:
> mAsterdam wrote:

>>W = {Mon, Tue, Wed, Thu, Fri, Sat, Sun}

>
> That's a ring (modulo), which is not a metric space.
>

>>d(Mon, Fri) = 4
>>d(Fri, Mon) = 3

>
> d(Fri, Mon) = |4 + 7n|, days, for any integer n. Which includes both cases:
> n=0 and n=-1.
>
> One could consider classes of equivalence { k + 7n } = k* as "distances",
> which is again the same modulo. Unfortunately k" are incomparable, as it
> expected from distances.
>
> If we wanted to make it a space, we should probably return back to the time
> space.
>
> Fri - Mon (this week) = 4 days (a vector, with a magnitude of duration)
> Mon - Fri (adjacent week) = -3 days (another vector)

I apologize to the other readers for my ignorance. Not to you, you clearly enjoy explaining ;-)

Thank you for your explanation.
Could you recommend a book?

-- 
"The person who says it cannot be done
should not interrupt the person doing it."
Chinese Proverb.

Received on Sat Jun 24 2006 - 14:34:14 CDT