Re: Nulls, integrity, the closed world assumption and events
Date: 8 Jan 2007 05:05:52 -0800
Message-ID: <1168261552.038820.270210_at_i15g2000cwa.googlegroups.com>
David wrote:
> Cimode wrote:
> No. If we show p => q and p is false then we can't deduce q is false.
Sure, but if proposition P is FALSE, we certainly even less deduce that
Q would be TRUE. Which is exactly what you do by considering the
person set in some hierarchy necessarily has an infinite number of
elements. As I told you Closed world assumption does not allow you to
make such inference....
> My point is that the following six conditions can't all be satisfied at
> once
> C1. use person(P,M,F) relation
> C2. don't allow nulls in M,F
> C3. enforce referential integrity on M,F
> C4. only allow finite number of persons in the domain
> C5. there are no cycles in the family tree
> C6. there is at least one person
>
> Obviously we must have C4, C5 and allow C6. I suggest that C2,C3 are
> important and therefore C1 should be dropped. ie the person(P,M,F)
> relation itself is "bad". Do you agree?
I agree or disagree to points that make sense. I do not see sense in
the point you're trying to make...
Received on Mon Jan 08 2007 - 14:05:52 CET