Re: General semantics
Date: Fri, 21 May 2010 05:35:28 -0700 (PDT)
On May 21, 1:38 pm, Erwin <e.sm..._at_myonline.be> wrote:
> On 21 mei, 12:45, Nilone <rea..._at_gmail.com> wrote:
> > On May 21, 7:57 am, Clifford Heath <n..._at_spam.please.net> wrote:
> > > paul c wrote:
> > > > By unary relation I mean a relation with one attribute (which I think is
> > > > pretty standard lingo, surprised that anybody here wouldn't think that)
> > > Right, that's what I thought you meant. In which case, it could be a
> > > representation of either an existential fact type (an object type),
> > > or a unary predicate over one. The distinction is important. A unary
> > > predicate creates a subset of the object type it involves.
> > > This distinction was, I believe, the cause of your earlier disagreement.
> > > Further, a unary fact type does not have to be mapped as a unary relation.
> > > It could be represented as a boolean value in a table of that object type.
> > > > but I have no idea what a 'fact type' is. I know of relation and tuple
> > > > types but don't know what use terms like 'fact type' or 'unary fact'
> > > > terms might have.
> > Perhaps, fact type = intension while unary fact = proposition
> Instantiating a predicate with attribute values always yields a
> proposition, no matter what the degree of the relation is.
Thanks for the correction. Let me try again: it seemed to me that Clifford's unary fact types correspond to propositional functions, while his unary facts correspond to the propositions yielded by instantiating such a type. As such, I see no real argument between the models; in fact, the little I know of ORM (mostly from looking at Halpin's page a while back) seemed to match up with the relational model well. Received on Fri May 21 2010 - 07:35:28 CDT