LC Responses/MZ1

From OWL
Revision as of 17:32, 25 March 2009 by IanHorrocks (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

Alan is concerned about citation of our meeting minutes. See message Michael Zakharyaschev <michael@dcs.bbk.ac.uk

To: Michael Zakharyaschev <michael@dcs.bbk.ac.uk
CC: public-owl-comments@w3.org
Subject: [LC response] To Roman Kontchakov & Michael Zakharyaschev

Dear Roman and Michael,

Thank you for your comment
     <http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0019.html>
on the OWL 2 Web Ontology Language last call drafts.

Your comment is closely related to the one by Maurizio (see http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0014.html) and Ivan (see http://www.w3.org/mid/49881F19.7040209@w3.org).

The working group has decided to implement the editorial changes and will correct the typos, thanks for pointing them out. We have also decided to add to OWL 2 QL reflexive, irreflexive, & asymmetric property axioms. Moreover, we will fix the inaccuracies in the complexity table, following your suggestions and discussions with Maurizio: for data complexity, we will add that OWL 2 QL is in AC_0, i.e., queries are first order rewritable and that the taxonomic complexity is NLogSpace-complete. Finally, we have decided *not* to add sameAs to OWL 2 QL, but to add a paragraph that explains that, if one wants to handle ontologies that are OWL 2 QL plus sameAs, then one can use a preprocessing step that materializes the sameAs relation and uses it in query answering procedures to simulate individual equality reasoning (see http://www.w3.org/2007/OWL/wiki/Profiles#Feature_Overview_2).

Please acknowledge receipt of this email to <mailto:public-owl-comments@w3.org> (replying to this email should suffice). In your acknowledgment please let us know whether or not you are satisfied with the working group's response to your comment.

Regards,
Uli Sattler
on behalf of the W3C OWL Working Group



CUT AND PASTE THE BODY OF THE MESSAGE (I.E. FROM "Dear" TO "Group") INTO THE BODY OF AN EMAIL MESSAGE. SET THE To:, CC:, AND Subject: LINES ACCORDINGLY.

PLEASE TRY TO REPLY IN A WAY THAT WILL ALLOW THREADING TO WORK APPROPRIATELY, I.E., SO THAT YOUR REPLY CONTINUES THE THREAD STARTED BY THE ORIGINAL COMMENT EMAIL



From http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0019.html

We have two comments on OWL 2 QL, document 7:

1. In section 3.1 it's written that "the following constructs are not supported in OWL 2 QL:

....

- reflexive properties

- irreflexive properties

- asymmetric properties

- equality (sameIndividual)

In fact, as shown in [1] below, one can (easily) reduce (in LogSpace) query answering in OWL 2 QL extended with the above mentioned constructs to query answering in OWL 2 QL as defined in the document (that is, without those constructs). Thus, the data complexity remains in LogSpace, and so the constructs CAN BE INCLUDED in OWL 2 QL without changing complexity.

Furthermore, if we add

- transitive properties

then query answering becomes data complete in NLogSpace.

2. In Section 5, Table 10, it's written that taxonomic complexity and combined complexity of OWL 2 QL is in PTIME. In fact, it NLogSpace-complete, even with all the constructs mentioned above.

[1] A. Artale, D. Calvanese, R. Kontchakov, and M. Zakharyaschev, The DL-Lite family and relatives. Available at http://www.dcs.bbk.ac.uk/~michael/DL-LiteFamily.pdf