Re: Guessing?

On Jul 31, 10:01 am, "Brian Selzer" <br..._at_selzer-software.com> wrote:
> "David BL" <davi..._at_iinet.net.au> wrote in message

> > Given relation r, let X(r) be the boolean valued characteristic
> > function of r.
>
> > Consider the following definitions
>
> > 1. OnTheTeam_r : the relation value recorded by the DB
> > 2. OnTheTeam_i : the internal predicate recorded by the DB
> > 3. OnTheTeam_e : the external predicate meant to represent reality
>
> > Is CWA associated with saying:
>
> > a) OnTheTeam_i = X(OnTheTeam_r) or
> > b) OnTheTeam_i = OnTheTeam_e?
>
> > You appear to suggest CWA implies both a) and b). Is that right?
>
> The closed world assumption involves what can be proved rather than what
> something means; an external predicate involves what something means;
> therefore, the closed world assumption is not associated with saying b). On
> the other hand, it is associated with saying:
>
> c) OnTheTeam_i --> OnTheTeam_e
>
> since whenever ~OnTheTeam_e, ~OnTheTeam_i.

I think you have that arse about. c) is assumed under OWA or CWA. If anything the CWA means that a missing tuple in the DB implies the negation of the proposition in reality.

Also, you say CWA is concerned with what can be proved, and therefore isn’t related to an external predicate (because it is informal) and yet c) refers to an external predicate. Received on Thu Jul 31 2008 - 05:43:33 CEST