Re: Nulls, integrity, the closed world assumption and events

"David" <davidbl_at_iinet.net.au> wrote in message news:1168390415.964551.175490_at_p59g2000hsd.googlegroups.com...
>
> JOG wrote:
> > Bob Badour wrote:
> > > JOG wrote:
> > > > Bob Badour wrote:
> > > >
> > > >>Marshall wrote:
> > > >>
> > > >>>On Jan 8, 4:44 am, "David" <davi..._at_iinet.net.au> wrote:
> > > >>>
> > > >>>>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?
> > > >>>
> > > >>>This analysis looks right to me.
> > > >>
> > > >>Huh? Your solution basically achieves all of the above with the
> > > >>inconsequential difference that you used a different name for the
> > > >>relation in C1.
> > > >>
> > > >>Nowhere above does it mention the very consequential difference in
> > > >>referential integrity constraints, which is in fact the straw in the
man.
> > > >
> > > > Hi Bob, if you were referring to my post then your last statement
isn't
> > > > true. I emphasized the change in referential integrity constraints
as
> > > > being important:
> > >
> > > You emphasized it and then David ignored it in his reply. If you look
> > > carefully, I think you will agree what you wrote appears "nowhere
above"
> > > where I wrote "nowhere above".
> > >
> > >
> > > > JOG wrote
> > > >
> > > >>where P is the candidate key of _parentage_, but where P, M and F
have
> > > >>enforced referential integrity (with a check constraint on sex) back
to
> > > >>the _person_ relation
> > > >
> > > > Either I've missed your point or you had a heavy new years
celebration
> > > > this year!
> > >
> > > You missed the point that David constructed a straw man by ignoring
your
> > > point entirely.
> >
> > Gotcha. All is clear. Happy new year.
>
> You understand what Bob is saying!
>
> My discussion about C1-C6 was in reply to Cimode and had nothing to do
> with your post.
>
> I agree with everything in your post(s). In fact I thought it
> basically reiterated my original post that suggested we should choose
> relations that avoid nulls. Your parentage relation and my mother and
> father relations were similar. I admit I failed to state explicitly
> the important fact that referential integrity was back to the second
> person relation that I defined after *removing* the (foreign key)
> parent attributes - I assumed that was obvious. After all, what else
> could I possibly have intended when I claimed that nulls were bad,
> referential integrity was important, and therefore dropped
> person(P,M,F) in favour of the following predicates
>
> person(P) :- P is a person
> mother(M,C) :- M is the mother of child C
> father(F,C) :- F is the father of child C
>
> Bob is confused when he says I ignored your point or constructed a
> straw man. This is my theory of what actually happened...
>
> Bob has a practice of using an email filter so his reading of a thread
> is very fragmented. Evidently he was unaware of my exchange with
> Cimode and when Marshall agreed with my statements about C1-C6, Bob
> assumed this indicated I disagreed with you!!! I find it pathetic,
> ridiculous and ultimately amusing that he tries to engage in a thread
> for which he has no understanding of the structure.
>

Perhaps we need to invent the term "metacrank". Received on Wed Jan 10 2007 - 15:23:05 CET