- From: pat hayes <phayes@ai.uwf.edu>
- Date: Mon, 12 May 2003 17:59:19 -0500
- To: jjc@hpl.hp.com
- Cc: www-webont-wg@w3.org
- Message-Id: <p0521062cbae5be763b0d@[10.0.100.5]>
I'm looking at http://www.w3.org/2002/03owlt/editors-draft/draft/ dated 12 May 4.2.1 (suggestion) Might be better to allow a syntax checker to ignore some lower levels, eg I'd be very happy with an engine that would say 'DL' for Lite docs as well as DL-not-Lite ones. 4.2.2 Er... I'm embarrassed that I don't know the answer to this, but is it really the case that any Lite ontology is consistent in Lite iff it is consistent in Full? Is there a proof of that somewhere? The terminology "complete" here is unfortunate as it is in conflict with established usage of this term in logic. I would suggest either using this term in conformance with its standard usage, or else use a different term. In fact, I would suggest a more thorough rewriting of this section. (I am willing to draft an alternative if that would be helpful. ) [Added later: I see that you credit Ian with help on this section. I think the three of us could agree on a suitable wording reasonably quickly.] It is written in a style which suggests, potentially misleadingly, that consistency and inconsistency checking are somewhat symmetrical, or even two aspects of one problem. In fact, they are sharply different in complexity for most languages, and inconsistency detection - but not consistency detection - is closely related to entailment. So I would suggest the following: distinguish a consistency checker (responses are Con/unknown) from an inconsistency checker (Incon/unknown), and define 'complete' for both of them thus: A[n in]consistency checker is complete if, whenever its input document is [in]consistent, it would eventually (given unlimited, but finite, resources of memory and time) return the answer '[In]consistent'. Then say a checker is decisive (new word, avoids the 'decision procedure' terminology) if it is both a complete consistency checker and a complete inconsistency checker. Then remark that there are no decisive checkers for OWL-Full but there are for OWL-Lite and OWL-DL. Simpler (editorial) option: replace 'complete' with 'decisive' (or some other word which is not a standard logical term) in current definition and rest of text. Another idea: allow three responses (four for a double-sided checker) where 'unknown' means 'dunno, run out of energy' and 'indeterminate' means 'can't figure because of network error or some such'. Then you could allow a complete implementation to return 'indeterminate' but not 'unknown'. Roughly, this distinguishes inability to answer based on internal versus external issues. Completeness relative to externals is obviously impossible to guarantee, is the point. Im a bit worried about stating completeness in the presence of datatypes. Your definition is behavioral - it talks about what the software delivers - and it uses the words 'with respect to datatypes'. Does this mean that consistency wrt one set of datatypes is different from consistency wrt a different set? In what way does a SET of datatypes affect the BEHAVIOR of a piece of software? You do not specify any connection between datatypes and software. I think this needs to be spelled out a little more carefully (define it wrt a datatype API, maybe? ) The final NOTE in this section refers only to DL and Lite: why? This is characteristic of all forms of completeness. Why are there not parallel definitions of an entailment checker, with conforming definitions of completeness, correctness etc. ? It would seem to be easy enough to state these in parallel to those in section 4.2. These notions would be a lot more useful in practice. The English gloss on some of the tests (eg http://www.w3.org/2002/03owlt/editors-draft/draft/byFunction#function-FunctionalProperty refers to 'arcs', which is a term that is now deprecated by the RDF WG. Might this be better phrased? Example: If prop belongs to owl:FunctionalProperty , and subject denotes a resource and has two outgoing prop arcs, then the object s of these arcs have the same denotation. Hence an arc originating in object1 can be copied to object2 . / If prop belongs to owl:FunctionalProperty , and subject denotes a resource which is the subject of two prop triples, then the object s of these triples have the same denotation. Hence any assertion made using one of them can be transferred to the other. In general, perform substitutions 'has FOO incoming prop arc' /'is the object of FOO prop triples' 'has FOO outgoing prop arc' /'is the subject of FOO prop triples' No other complaints. Full marks on layout, overall document structure, etc., and extra credit for C.5.1 :-) Pat PS. The Ntriples turquoise background looks rather dark and menacing on my screen. Somewhere closer to #c0e0e0, maybe? -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32501 (850)291 0667 cell phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes s.pam@ai.uwf.edu for spam
Received on Monday, 12 May 2003 18:59:22 UTC