Teleconference.2008.02.27/Minutes

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1. Agenda amendments - none
2. Minutes

PROPOSED: accept previous minutes http://www.w3.org/2007/OWL/wiki/Teleconference.2008.02.20/Minutes

Peter Patel-Schneider: +1
Zhe Wu: +1

RESOLVED: accept previous minutes http://www.w3.org/2007/OWL/wiki/Teleconference.2008.02.20/Minutes

3. Upcoming RDB2RDF incubator group discussion
Michael Schneider: What is the incubator group?

Ivan Herman: The incubator group is finally looking at ways of mapping relational data to RDF. This is relevant to this group in that they are interested in mapping relational data to owl structures. If all goes as planned, it will be announced tomorrow. It will be announced on the home page as well. The charter URL is not available yet.


Ian Horrocks: This is something we would just want to keep an eye on, but not much to do now.

James Hendler: I just wanted to say that the incubator group is directly related to the discussion on fragments; the work is related to SQL queries, so we need to pay close attention to this. We should make sure that the coordination group makes sure that we don't work at cross purposes.

Ian Horrocks: So should we consider nominating someone to coordinate with this group?

Ivan Herman: I propose we should wait a week and look at the charter first. Note that the chair is from Oracle.

Pending Review Actions Discussion

1. Ian Horrocks: There was agreement that Boris would update the spec to address Issue 95 any objection?

Evan Wallace: I brought up in email that figure 5 does not completely reflect the change.

Ian Horrocks: Is that the only problem, that figure 5 needs fixing?

Evan Wallace: I didn't particularly like the resolution either, but given the resolution, yes.

Boris Motik: What's wrong with the figure?

Peter Patel-Schneider: figure 5 is also wrong for me

Evan Wallace: It should point to a Datatype rather than DataRange

Jeff Pan: URL?

Boris Motik: That's been corrected - you might need to refresh your cache.

Ian Horrocks: Peter also says this is a problem for him.

Peter Patel-Schneider: but refreshing fixes it
Uli Sattler: fig 5 on http://www.w3.org/2007/OWL/wiki/index.php?title=Syntax

Michael Schneider: What about the other document, the semantics and RDF mapping ... which is a little bit confusing.

Ian Horrocks: Are you asking about interactions with other documents?

Michael Schneider: Yes, interactions between the syntax document and other documents on this issue.

Jeff Pan: uli, thanks!

Boris Motik: I need to check the documents...

Ian Horrocks: We may not be able to resolve this today (Issue 95), thus it may need revisiting next week.

Boris Motik: I don't think the other documents need to change, but perhaps other people have other opinions.

Ian Horrocks: Perhaps we should come back to this next week for a definitive answer.

Peter Patel-Schneider: semantics has to change, but only very little

Ian Horrocks: Let's leave this as pending and revisit it next week.

Boris Motik: ok

Evan Wallace: After refreshing I do see the change in Figure 5!
2. Ian Horrocks: Action 87, which Alan has completed ... are we happy with what Alan has written there?

Ian Horrocks: Action 87: Complete

3. Ian Horrocks: Action 92: Peter to write up his understanding of Issue 68.
Michael Schneider: +1 to peter's mail
Jeremy Carroll: +1

Ian Horrocks: Action 92: Complete

Due and Overdue Actions Discussion

1. Ian Horrocks: Action 72: Continues
2. Ian Horrocks: Action 79: Continues
3. Ian Horrocks: Action 90: Continues

Jeremy Carroll: Will try to get it done for next week.

4. Ian Horrocks: Action 42: Bijan, who isn't here - Continues
Uli Sattler: Bijan said he was working on it
5. Ian Horrocks: Action 86: Continues
Jeremy Carroll: ditto

Jeremy Carroll: pending for next week

Jeremy Carroll: jeremy; a lot of HP work on at the moment, should ease off at easter

Publication Schedule

Ian Horrocks: Publication schedule - there is an issue from Boris regarding updating the public working drafts, which documents we might want to publish. Would we want to update the current working drafts or potentially publish other documents?

Ian Horrocks: Boris proposes that at least the current 3 documents that are working drafts should be updated.

Sandro Hawke: The motivation doesn't make sense to me; we can make snapshots for the working group, but the reason to publish new working drafts is to get feedback from outside the working group.

Ian Horrocks: This is a good point, have the documents changed sufficiently that we would want outside feedback?

Jeremy Carroll: I think that it is good to show that we're aligned, if we are...

Sandro Hawke: The work in making another working draft is to publish a note to the public that there is another working draft, and then to publish it. If there are changes worth sharing, then sure, let's republish.

Ian Horrocks: Several people mentioned publishing the XML syntax, two things to discuss - A, are the changes sufficient to publish new versions, and B should we consider publishing additional documents.

Boris Motik: I think it would be good to show that we are aligned and something has changed. I also think we have fixed quite a few bugs, and coming up with a list of the issues we've fixed might also be good. We should consider the XML syntax and also the RDF mapping.

Boris Motik: The other document we should publish is the XML syntax, if we can achieve resolution on the fragments then we should consider that as well.

Ian Horrocks: I don't think that the fragments are ready yet...

Jeremy Carroll: I'm in principle in favor of publishing the XML syntax, but we should add having a GRDDL profile to the issue list.

Ian Horrocks: yes I think that's appropriate.

Jeremy Carroll: ok, I'll do that

Ian Horrocks: Nobody else expressed anything about the other working drafts ... don't know whether that speaks for or against republishing... Perhaps if we publish both the documents and a list of the issues that have been addressed / changed / fixed that would be useful.

Ian Horrocks: Should we re-publish new version of the three already-published documents? We could take a straw pole on whether we should publish new ones. Perhaps we should do this doc by doc? Who thinks the structural syntax has changed enough?

PROPOSED: Syntax?

Ian Horrocks: ok, so generally positive on structural syntax. Same question on the semantics document.

PROPOSED: Semantics?

Ian Horrocks: Do we need a formal resolution to publish?

Sandro Hawke: yes, with regard to publishing, we should.

Jeremy Carroll: I feel that we should have addressed 1 or 2 of the harder issues before republishing.

Jeremy Carroll: We've done quite a bit of cleaning up, but something new would be more interesting -- I'm not convinced that it's work the effort.

James Hendler: My real fear is of exhausting people - if we republish for minor issues, people won't really look when we re-release for major issues. We run the risk of getting to CR and having people raise more difficult issues.

Sandro Hawke: If we publish with a list of the things we've addressed, and then ask for feedback does that make sense?

James Hendler: My sense is that people don't read the status section, and I would prefer we fix some more substantive issues before publication.

Jeremy Carroll: We can meet the heartbeat status by publishing other documents.

Ian Horrocks: Ok, Perhaps we should see if we can resolve a few more of these issues before publishing...

PROPOSED: Semantics -- republish?

Ian Horrocks: So not very strong support for that, how about the RDF mapping document?

PROPOSED: republish RDF Mapping?

Ian Horrocks: So similarly, not tremendously strong support for that. So the other issue is whether or not to go forward with any of the other documents, modulo resolving the GRDDL issue with the XML syntax document. How many feel we should publish that?

PROPOSED: XML syntax to FPWD

Michael Schneider: I need time to read this document before I say anything about it.

Ian Horrocks: It has been on the wiki since the working group started ...

Ian Horrocks: We have homework to do, potential issues with respect to GRDDL, and then we can think about a potential proposal to publish.

Proposals to Resolve Issues

Ian Horrocks: This needs to be postponed to next week.

Michael Schneider: Issue 95 is only about this compatibility table, it may make sense to close this and open another regarding datatype restrictions.

Boris Motik: I actually think this is difficult to split, the table by itself is meaningless unless you say how you are applying it. When I entered this issue, I thought these two things had to be considered together. I do agree that we probably need something like named datatypes, but this issue is about fixing an error, modulo fixing the other docs. If there are other features we should discuss them separately, and limit scope.

Ian Horrocks: We should try to keep issues fairly scoped; there are a few details that you didn't get to, but hopefully they will be resolved by next week.

General Discussion

Ian Horrocks: Next issue is OWL 1.1 Full. Some of the issues related to OWL 1.1 Full are some of these difficult issues to which Jeremy was alluding when we discussed publication. We need to figure out generally how we're going to go forward on OWL 1.1 FUll, who is going to address the semantics.

Ian Horrocks: Are the semantics going to be completely new, who is going to do the work, anybody interested in doing the work?

Michael Schneider: I offer to expand the semantics to cover the new constructs ... I would need a lot of people to look over what I do if I do it. I could expand the semantics to include the new constructs as they are, but would need significant review.

Jeremy Carroll: I would offer to review / play a supportive role of the sort Michael is asking for.

Ian Horrocks: Is this the right way forward, or would we prefer to look for completely new semantics?

Jeremy Carroll: Bijan had a proposal for completely new semantics that I've lost track of, he's not on the call...

Ian Horrocks: So what do you think about this Jeremy - about extending the existing semantics?

Jeremy Carroll: To me this shouldn't be too difficult to extend the existing semantics ...we've hit an issue with the QCRs that needs to be addressed ... the property change looks quite straightforward to me. The issues are going to be where it interacts with other things, such as reification.

Ian Horrocks: Quite alot of the other issues are not saying ... there is a known problem here ... we need to discover whether there really. is an issue here, and then figure out how to address it. We seem to have a way forward here.

Michael Schneider: I think the best would be to follow what ... was done a few weeks ago, a proposal for semantics with considerations, then we can look at what the problems are.

Jeremy Carroll: We could go for a public working draft that is essentially a diff -- here are the new bits, that will be converged with the older version eventually. Clearly by working draft 2 or 3 we would actually need to do the merge.

Ian Horrocks: We should have an action on Michael to do this ... Michael, how long do you need for this ...

Michael Schneider: Since I have already done some preliminary work, we could have the start of a wiki for F2F2. A wiki version, which has language constructs and related semantics and considerations for F2F2, not a full draft, which will take a lot of writing.

ACTION: Mschneid will initiate work on the OWL 1.1 Full semantics, with a draft posted to the wiki a week prior to the next F2F meeting.

Michael Schneider: It's a layered architecture, might use a rule-based semantics, taking the lead from the semantics for RDFS ... could specify this with a rule-based semantics - I think this fragment would be a good place to start

Jeremy Carroll: Is the proposal that we should define OWL prime fragment by a set of rules that would give a minimum level of entailment?

Ian Horrocks: This is something that isn't completely clear in the email on this fragments thread.

Michael Schneider: The completeness stuff I'm planning to address in email.

Jeremy Carroll: and also what we mean by completeness...

Michael Schneider: There are a few things to consider, I will respond in email.

Ian Horrocks: This is a complex issue, so we should wait for follow up in email.

James Hendler: There is a thread that has gone off into PD* completeness that started with a thread on OWL prime completeness ... are these two divergent threads?

Michael Schneider: The problem is that owl prime is a moving target ... I think it has the possibility to converge.

James Hendler: ok, then I'll wait to see what happens.

Ian Horrocks: It will help a lot to have the extended owl full semantics, which is significant progress.

Ivan Herman: The pD* and owl prime were all rule-based features in OWL 1.0, but when we look at the features to be added in OWL 1.1, there may be things worth investigating.

Zhe Wu: To Michael's comments, if he can come up with a set of rules for OWL full I will be happy to review them, then. With respect to OWL 1.1, I think the property chains can be addressed with a few rules.

Michael Schneider: I think we have in mind OWL 1.1 features ... the question was where we don't have to do too much ourselves using the pD* paper going to OWL 1.1 features, we will have to address this ourselves, especially with respect to completeness.

Jeremy Carroll: I think the pD* design has some fairly clear principles, which can guide what should be included and what can't be. We could use these design principles to extend OWL prime as a result.

Ian Horrocks: The main object of this discussion was to make progress on OWL Full semantics, which we have.

Issue Discussions

Ian Horrocks: Issue 3 - anonymous individuals ... there has been some traffic on this over the last few weeks ... are we any closer to a resolution on this?

Boris Motik: The last time there was a question as to whether it would make sense to have anonymous individuals as skolems. In the end, we don't know what the semantics of owl full are, so I don't see that we are losing anything by that.

Jeremy Carroll: So, I think it depends what we mean by compatibility, from one point of view it would be backwards compatibility and another the forward view. It would allow us to deal with more graphs.

Ian Horrocks: Pragmatically it wouldn't be any different, since people are doing this in practice.

Boris Motik: Pragmatically this would bring the spec in line with implementations in OWL DL. I see this as an improvement rather than a disadvantage in OWL DL. We don't know whether OWL Full model theory is satisfiable, so we are being forced into thinking about this for the sake of some phantom compatibility issue.

Uli Sattler: I just wanted to make similar points - it would indeed cover more realistically what people have implemented and expect as answers. It also reflects what people can implement - it would be extremely difficult to come up with a treatment of bnodes that would not be skolemized.

Ian Horrocks: It seems that several people have agreed with this point, even Jeremy is softly in agreement with this... so we might be in a position to agree that this is a way to address this issue.

Jeremy Carroll: I would need to vote against such a proposal at the moment.

Jeremy Carroll: I have a mandate from HP to oppose this at the moment - I can see the arguments, and for now it would be a vote against.

Ian Horrocks: Would anyone else be in a similar position to Jeremy, who would need to vote against?

PROPOSED: resolve issue-3 by having Skolem semantics in DL

Jeff Pan: I have the impression that we had discussion about the differences in the semantics, if you have unique names assumption, it is easy to show the differences, I'm not sure what people will say at the end of the day.

Boris Motik: I don't think this is the case, especially with the unique names assumtion, since OWL doesn't support this, you would have to axiomatize this yourself. Under OWL DL semantics you would have to deal with this yourself.

Ian Horrocks: I suggest that Boris writes up a kind of precise specification of what the solution would be, in the meantime Jeremy will attempt to discuss this internally to get a view of the HP position.

Ian Horrocks: If we have a complete proposal, we can move it into the issues to resolve.

ACTION: bmotik2 to Write up a precise proposal on how to resolve ISSUE-3

AOB

Ian Horrocks: AOB?

James Hendler: Some pieces of work get to move ahead because people in the same organization are able to make space and work on them. With respect to other things, such as fragments, we should think about how to get the work done in the context of the working group, perhaps a task force to do this.

James Hendler: Now that we have sort of the gist, we should get people to move forward on the work.

Ian Horrocks: The way we've done this up until now was to use the wiki, admittedly we've tasked Michael to do the OWL semantics, but he was a volunteer. I think I proposed in an email that we needed to come up with a document regarding fragments, then we can discuss how to operationalize next week.

Uli Sattler: Perhaps we could do a search for people who would be willing to work on OWL prime - we don't know who would like to put in some effort here.

Ian Horrocks: This is why I sent the email, and was hoping people would step forward.

Jeremy Carroll: On owl prime, there is the whole patent policy issue.

Ian Horrocks: It would have been great to have Herman, but we have others in the WG with expertise.

Jeremy Carroll: This is a very good point - it is plausible that pD* has patent protection from Philips - we should be able to check this as it would have been published by now.

Ian Horrocks: We haven't necessarily decided that it would be based on pD*.

James Hendler: I'm not necessarily against pD*.

Ian Horrocks: I'll resend this email and people can respond that they would like to work on this after the telecom.

Zhe Wu: I just want to clarify that the set of rules have to be complete?

Ian Horrocks: I don't think we can figure this out today, but it's a good point for people to figure out once they start working on the document.

Ian Horrocks: any other other business?