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Re: OWL Lite semantics

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Mon, 09 Dec 2002 16:09:02 +0000
Message-ID: <3DF4C01E.3030309@hpl.hp.com>
To: Ian Horrocks <horrocks@cs.man.ac.uk>
CC: Jim Hendler <hendler@cs.umd.edu>, Jeremy Carroll <jjc@hplb.hpl.hp.com>, www-webont-wg@w3.org

(This responds in part to the points raised by Ian, Pat and Peter).

I think I would rather pose the proposal as a proposal to bless a 
particularly style of incomplete reasoning.

Seen from an OWL Full perspective ...
OWL DL reasoners must be complete with respect to OWL DL semantics and 
sound with respect to OWL Full semantics.
Any non-OWL DL entailments found can be distinguished since either the 
premises or conclusions are syntactically excluded from OWL DL.
However, at one level an OWL DL reasoner is an incomplete OWL Full reasoner.

Similarly, under my proposal an OWL Lite reasoner must be complete with 
respect to the proposed OWL Lite semantics, and sound with respect to the 
OWL Full semantics. This seems wholly analogous, and will introduce no new 
practical problems, since the reality is that not every OWL Lite system 
will provide complete reasoning with respect to the OWL DL semantics over 
the OWL Lite subset. By giving developers a lower bar to aim at, we can 
reasonably expect them to hit it, thus aiding interoperability by giving 
clear (and achievable) subsets to aim at.

I will respond to the requirement to justify the achievability claim later. 
(tomorrow or wednesday).

In my opinion, it is unrealisitic to expect all OWL Lite developers to 
achieve complete reasoning with repect to the current OWL DL semantics over 
the current subset. We need to do one of:
- make the subset smaller
- bless some form of incompleteness
- change the OWL DL semantics

I see my proposal as blessing a form of incompleteness.

A motivation for expressing it in terms of another semantic theory is to 
ensure some hard and fast criterion rather than my woolly 80% type attempts 
earlier. I particularly noted John Stanton's opposition to that proposal.

Jeremy
Received on Monday, 9 December 2002 11:09:19 GMT

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