Re: Constraints and Functional Dependencies

On Feb 24, 9:25 am, mAsterdam <mAster..._at_vrijdag.org> wrote:
> Marshall wrote:
> > mAsterdam wrote:
> :-)

Smiley back at ya!

> About the other side of this medal:
> just a few days ago (feb 21, nntp.perl.org)
> Steve Lukas wrote in perl.per6.language:
> > My approach is:
> > In terms of writeability a variable/reference can be
> > (1) a variable, (2) a constant or (3) a "final"
> > (Don't wonder if you never heard of that "final", just my proposal)
> > That means it can be writeable (1),
> > not writeable since compile time (2) or
> > not writeable since that moment in runtime when it gets "final" (3).

Interesting. Aside: perl6 seems to be having a strange, strange gestation.
It's hard to imagine Haskell and Perl working together.

> [snip suggestion to prime all instances]
>
> > I am sensitive to the concern you mention, however I
> > think it will be okay as is. (Although I admit I am not
> > a teacher.)
>
> Yes you are.

Wow. Thanks for that.

> >>> What about candidate keys? Suppose we have a relation R with
> >> ... only the ...
>
> >>> *sets* of attributes A and B: R{A, B}.
>
> > I debated whether to make that specific or not. Yes, the
> > two are only equivalent if all attributes of R are in A union B.
>
> > My intent is to express that with R{A, B}.
>
> ISTM making this one explicit goes better with the minimalist approach.
> The less is to be assumed ... grmpf!
> I just saw a razor blade fly by :-)

Ha! It took me a minute to get that.

Marshall Received on Sun Feb 25 2007 - 00:24:55 CET