Re: FOL/HOL: is there a middle ground?

"Ralph Becket" <rafe_at_cs.mu.oz.au> wrote in message news:3638acfd.0407191600.411bb49f_at_posting.google.com...
> "Marshall Spight" <mspight_at_dnai.com> wrote in message news:<ZqIKc.113980$MB3.14356_at_attbi_s04>...
> >
> > Actually, all I want is relation-valued attributes and list-valued
> > attributes.
>
> I can understand why you'd want list-valued attributes. Speaking as
> a logic programmer, it's not clear to me why modern DBMS don't come
> with strong, expressive, statically checked type systems for attributes.

Yeah.

> For instance, being able to define a `maybe' type would solve all those
> problems with NULLs right off the bat.

Yeah!!!

> But I still don't understand *why* you'd want relation-valued attributes
> if you're going to restrict yourself to finite relations. Surely you
> could get most of that functionality using names. For example:
>
> binop A B AopB
> --------------------
> "or" F F F
> "or" F T T
> "or" T F T
> "or" T T T
> "and" F F F
> "and" F T F
> "and" T F F
> "and" T T T
> "xor" F F F
> "xor" F T T
> "xor" T F T
> "xor" T T F

I completely didn't understand this example. What's supposed to mean what here? Where's the RVA-equivalent?

Marshall Received on Tue Jul 20 2004 - 04:42:35 CEST