Re: more closed-world chatter

On May 6, 2:51 am, Marshall <marshall.spi..._at_gmail.com> wrote:
> On May 5, 10:04 am, "David Cressey" <cresse..._at_verizon.net> wrote:
> > "David BL" <davi..._at_iinet.net.au> wrote in message

[snip]

> > > IMO it's confusing to talk about taking a "union of the constraints".
> > > In a sense you are aggregating them. I would call it an ANDing of
> > > constraints as boolean valued expressions, which leads to set
> > > intersections not unions.
>
> > Sorry to add to the confusion, but I will: the union of the constraints
> > yields the intersection of the data. Clear as mud?
>
> Yes, exactly.
>
> All the constraints that apply in a given context could be thought of
> as a set, or they could be thought of as a single constraint, with
> the terms ANDed together. Furthermore, a single constraint can be put
> in Conjunctive Normal Form and each term can then be separated.

I'm not sure whether the concept of a set of constraints is well defined in general, given that conjunctive normal form only applies to expressions within the confines of boolean algebra. Received on Sun May 06 2007 - 14:53:58 CEST