Re: Character string relation and functional dependencies

On Dec 6, 7:54 pm, paul c <toledobythe..._at_ooyah.ac> wrote:
> Marshall wrote:
> > On Dec 6, 10:15 am, Tegiri Nenashi <TegiriNena..._at_gmail.com> wrote:
> >> On Dec 6, 9:40 am, rp..._at_pcwin518.campus.tue.nl (rpost) wrote:
>
> >>> Another difference is that database tables are finite and variable,
> >> Oh, relations in database world are certainly not restricted by finite
> >> cardinality.
>
> > Neither is it restricted to variables--not only in papers and in
> > theory
> > but in practical terms.
>
> Marshall, why do I get the feeling you are drifting the theme? (which
> coming from you would be absolutely okay by me, but this seems a bit
> cryptic to me and I wonder if you care to expand?)

Well, if nothing else, we can certainly consider relation constants. DUM and DEE are certainly useful, and of course those are constants, not variables.

I also don't see anything wrong with considering, say, addition on arbitrary sized integers as an infinite relation, and reasoning about it accordingly. Yes, there are machine resource limits, but that doesn't have to limit our reasoning.

Also, I am working right now on the idea of a relational logic, so I spend a certain amount of time thinking about equations with table variables that I don't know much about. Sometimes not even the predicate.

I guess drifting the theme is something I do a lot. :-)

Marshall Received on Fri Dec 07 2007 - 07:34:03 CET