# Re: Constraints and Functional Dependencies

Date: 24 Feb 2007 08:53:14 -0800

Message-ID: <1172335994.298831.89100_at_8g2000cwh.googlegroups.com>

On Feb 24, 7:55 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:

*> Marshall wrote:
*

> > [...]

*>
**> Those look good to me. Domain constraints are very easy:
**>
**> forall R(a1,...an): a1 in d1 and ... an in dn
*

Does the term "domain constraint" mean anything different than "type constraint?"

> I don't know why you think one cannot express unboundedness--not that

*> the constraint is meaningful for finite computers.
**>
**> forall R(a): exists R(a'): a' = a + 1
**>
**> or
**>
**> forall R(a): exists R(a'): a' > a
*

One can express unboundedness, but since I was proposing limiting what one can quantify over to named relations, and since the natural numbers are something other than that, (an infinite set) my expressiveness restrictions make it impossible to express the unboundedness *of the natural numbers* specifically.

Marshall Received on Sat Feb 24 2007 - 17:53:14 CET