Re: DAML-S expressiveness challenge #1

Thanks, Ian, for the guidance.

[Ian Horrocks]


> >  If
> > you were using predicate logic or KIF, I imagine you'd arrive at
something
> > like this:
> >
> > for all persons x it is not true that:
> >     ((x bought diapers) and (x is not a parent))
>
> Using FOL is fine by me, although it has the disadvantage that the
> translation into DAML+OIL isn't always obvious. However, I don't think
> that what you have written does the trick - it certainly isn't
> equivalent to the "pseudo" DAML+OIL I wrote. As I understood it, we were
> trying to express that people buy diapers if and only if they are
> parents. What you have written says that people buy diapers only if
> they are parents. What you needed was to say:
>
> for all persons x it is not true that:
>     (((x bought diapers) and (x is not a parent))
>     or ((x not bought diapers) and (x is a parent)))
>
>

Hmm, I think this version does also say that there's no one who has bought
diapers who is not a parent, thus adding  the "if and only if" part; I
hadn't picked that up when I read the last few posts.

I wasn't offended by the pseudo-syntax, I just wasn't too sure how pseudo it
was!  Thanks.  On the other hand, see how easy it was to get the point
clarified for more discussion.  (Not that I'm a fan of reading lots of
predicate logic!)

Regards,

Tom P