Re: choice of character for relational division

From: David Cressey <cressey73_at_verizon.net>
Date: Mon, 02 Apr 2007 11:26:38 GMT
Message-ID: <OL5Qh.2160$k%2.660@trndny01>

"Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message news:Le5Qh.18375$PV3.190658_at_ursa-nb00s0.nbnet.nb.ca...
> David Cressey wrote:
>
> > "Marshall" <marshall.spight_at_gmail.com> wrote in message
> > news:1175468445.659304.173050_at_b75g2000hsg.googlegroups.com...
> >
> >>On Apr 1, 3:00 pm, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
> >>
> >>>David Cressey wrote:
> >>>
> > Marshall,
>
> I'm not Marshall, but I am answering anyway.
>
>
> > Why did they call it "relational division", anyway? Is there some
feature
> > of relational division that makes it reminiscent of arithmetic division?
I
> > can see how "cartesian product" is connected to "product". all you have
to
> > do is look at the cardinalities.
>
> Relational divide is to cartesian product as divide is to product.

Thanks for an excellent answer.

Marshall,

How do you represent cartesian product in your language?

is it: A * B ? Received on Mon Apr 02 2007 - 06:26:38 CDT