Re: Question: disjointness of classes and datatypes

Peter Crowther wrote:
> 
> > From: David Allsopp [mailto:dallsopp@signal.qinetiq.com]
> > However, this disjointness is not expressed in the language
> > specification of DAML+OIL
> > (http://www.daml.org/2001/03/daml+oil.daml) as
> > far as I can see.
> >
> > Is there a reason for this?
> 
> The language spec specifies the syntax of DAML, not its semantics.  In a
> couple of places you need to be able to specify that a class or a datatype
> could occur, so it's difficult to enforce the disjointness in the syntax.

Ah. I guess one would have to create a superclass of both Class and
Datatype. 

I was just curious as to why, for instance 
[Thing--complementOf-->Nothing]  is in the language spec, which looks
like semantic content to me, but not [Class--disjointWith-->Datatype],
that's all.

> If you want to find the formal basis, you'll need to look at one of the
> semantics docs: axiomatic or model-theoretic.  For example, check out the
> model-theoretic semantics at
> http://www.daml.org/2001/03/model-theoretic-semantics.html.  The key appears
> to be in the preliminary mappings to the two domains AD (abstract) and DD
> (datatype) plus the definitions of IC and IO.

OK, thanks.

David Allsopp
QinetiQ
UK

-- 
/d{def}def/u{dup}d[0 -185 u 0 300 u]concat/q 5e-3 d/m{mul}d/z{A u m B u
m}d/r{rlineto}d/X -2 q 1{d/Y -2 q 2{d/A 0 d/B 0 d 64 -1 1{/f exch d/B
A/A z sub X add d B 2 m m Y add d z add 4 gt{exit}if/f 64 d}for f 64 div
setgray X Y moveto 0 q neg u 0 0 q u 0 r r r r fill/Y}for/X}for showpage

Received on Thursday, 23 August 2001 08:56:21 UTC