Date: Thu, 24 Jul 2008 07:54:14 -0700 (PDT)
On Jul 24, 9:25 pm, "Brian Selzer" <br..._at_selzer-software.com> wrote:
> "David BL" <davi..._at_iinet.net.au> wrote in message
> > On Jul 24, 10:56 am, "Brian Selzer" <br..._at_selzer-software.com> wrote:
> >> > In a database encoding there is only a single defined interpretation
> >> > of the encoded attributes as values in the RM formalism. Therefore
> >> > there is no distinction between symbol and value that can be made.
> >> I don't agree. Under the domain closure, unique name and closed world
> >> assumptions, a database is a proposition that is supposed to be true.
> >> How
> >> the database is physically implemented is irrelevant.
> > A relation is formally defined as a set of tuples. Nothing more!
> There are several definitions, but that is neither here nor there.
> Relations were chosen because they look and behave a lot like the extensions
> of first order predicates. Of course the extension of a predicate includes
> both positive and negative formulae, but the closed world assumption enables
> the elimination of the negative formulae.
Well I'm not sure what the CWA actually means...
Does the CWA merely relate to the trivial association between a relation (formalised as a set of tuples) and its internal predicate (which is just the relation's boolean-valued characteristic function).
Alternatively does the CWA relate to an assumed association between a relation and an external predicate? If it is the latter then the CWA is clearly outside the RM formalism. Received on Thu Jul 24 2008 - 09:54:14 CDT