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

Brian Tkatch wrote:
> Cimode wrote:
> > David wrote:
> > > Consider the following relation
> > >
> > > person(P,M,F) :- person P has mother M, father F.
> > >
> > > By induction a non-empty
> > > database would have to be infinite.
> > A false premise makes all deductions coming from it false. Closed
> > World Assumption does not say anything about the number of element that
> > belong to a domain of values from which one attribute values are
> > derived. In the case of a *person* domain, the number of elements in
> > the set is certainly finite. Therefore, the number of propositions
> > involving person as an attribute is limited as well.
>
> Would not the question be better stated:
>
> If a table lists linked chains (with the linked-to link), how is the
> final link (whether first or last) stated?
>
> In such a case i link the item to itself.

You suggest a proposition stating that a person is their own mother/father? Received on Mon Jan 08 2007 - 17:18:26 CST