Re: relations aren't types?

"Alfredo Novoa" <alfredo_at_ncs.es> wrote in message news:e4330f45.0401030615.6f7b437a_at_posting.google.com...
> "Bob Badour" <bbadour_at_golden.net> wrote in message
news:<Pr6dnf10XP1_8WuiRVn-tw_at_golden.net>...
>
> > > > Since these are types with values and operations, how exactly do
they
> > differ
> > > > from scalar types?
> > >
> > > They have components, or user visible components if you prefer.
> >
> > You mean they have possible representations just like any other values.
>
> No, the contrary. I mean they have visible "structure", but not
> possible representations.
>
> What are the possible representations of a relation value?

One possible representation has a header and a body where THE_header is a set of attribute name/data type pairs and where THE_body is a set of sets of attribute name/data type/value triplets.

> I don't mean pictorial representations, of course. A table could be a
> pictorial representation of a relation, but it is not the same sense
> as in possible representation.

The possible representation above is not pictorial.

> Natural language is confusing.

Certainly, it can be.

> > > Scalar types does not have components, they have representations, and
> > > each representation may have several components or not.
> >
> > Since one representation of an integer is an array of bits, I guess that
> > means integers are not scalar. Right?
>
> They are scalars because they may have different representations.

Another representation of a relation has an array for each attribute.

I guess that means relations are scalars because relations may have different representations. Received on Sat Jan 03 2004 - 17:39:08 CET