Re: ISSUE: DAML+OIL semantics is too weak

> My messages
> http://lists.w3.org/Archives/Public/www-webont-wg/2002May/0143.html
> and
> http://lists.w3.org/Archives/Public/www-webont-wg/2002May/0146.html
> read
>
>     Ad/ :R a [ owl:complementOf :R ]
>
> on the line that you quote as
>
> > > > >      Ad/ :R a :R
>
> How did that get changed in your message?

I (normally) don't use my (silly) mail client
to reply to messages (it can't even do > stuff)
so I copy and paste in a text editor. It is
indeed bizarre and I can't explain it, but it
changed, I can see that. I did a lot of
cut-copy-paste and it took quite some time,
but I did not do that one on purpose ;-)

[...]


> I guess I was not clear enough.  Being more explicit, the proof would
> proceed along the following lines:
>
> | :R a :R              Assumption
> | :R a [ owl:complementOf :R ]   From a/, using modus ponens
> | FALSE                     From ?x a ?y, ?x a [owl:complementOf :y] ->
FALSE
> :R a :R -> FALSE       Discharging the assumption
> not(:R a :R)           modus tolens

I also use modus tollens (actually resolution)
quite a lot inside the engine, but it's not safe
I think as outside (non-closed world) evidence.

--
Jos