Teleconference.2008.04.23/Minutes

(Scribe changed to Martin Dzbor)

Agenda amendments

Alan Ruttenberg: we're starting

Alan Ruttenberg: F2F - discussed this with Ian and we're settling on 28-29 July at MIT, details pending

Alan Ruttenberg: want to include a topic on issues raised and how they are handled

Alan Ruttenberg: talking to IanH and things are going to change how issues are handled, raised,...

Alan Ruttenberg: there was an email about first batch of issues to review

Pending actions

Alan Ruttenberg: four points - update on RDF mapping (Action 115)

Alan Ruttenberg: Action 137, Action 120, Action 138

Action 115 Update the RDF mapping with the accepted resolution of Issue 12 as per Peter's suggestion/Boris

PROPOSED: the above actions to be considered done

Action 115 (Update the RDF mapping with the accepted resolution of Issue 12 as per Peter's suggestion/Boris)

Bijan Parsia: My overdue actions got siderailed by the easyclasskey discussion so remain undone

Bijan Parsia: should be done in a few days

Jeremy Carroll: to review doc on OWL compatibility with RIF - prob. mid May - in line with their schedule

RESOLVED: Action 137, Action 120, Action 138, Action 115 done

Previous minutes

Alan Ruttenberg: are minutes acceptable?

PROPOSED: Accept Previous Minutes (from 16 April)

RESOLVED: Accept Previous Minutes (from 16 April)

Raised Issues

Alan Ruttenberg: this section will be timed to 30 mins and we will return to issue later if time permits

Alan Ruttenberg: two raised issues - Issue 113

Alan Ruttenberg: Open/Shut per Jeremy's note (http://lists.w3.org/Archives/Public/public-owl-wg/2008Apr/0198.html)

Alan Ruttenberg: Issue 115 - icon needed for the WG pages

Alan Ruttenberg: this looks like minor change, not related to OWL

Alan Ruttenberg: Issue 120 - bug fixes to OWL 1 Semantics/Backwards compatibility

Alan Ruttenberg: considered editorial, already updated to reflect the issue

Alan Ruttenberg: any further issues?

Proposals to Resolve Issues

Issue 22 - Add sugar for rule (?x :hasSibling ?y) ^ :Male(?y) => (?x :hasBrother ?y)

Alan Ruttenberg: proposals to resolve issues

Alan Ruttenberg: Issue 22 - Syntactic sugar for role rules, is proposed to be considered closed, per this email

Alan Ruttenberg: we suggest to close it with no action

Markus Krötzsch: While rules are syntactic sugar, many applications of rules are prevented by current structural restrictions, even though the offending rules are not problematic in principle. We should be aware of that restriction. (see also this email) Alan Ruttenberg: does this problem affect specification? Markus Krötzsch: if you want to express... Jeremy Carroll: maybe we should postpone these issues to future WG-s? Uli Sattler: agrees to close this issue Uli Sattler: maybe consider this in the next extensions to OWL

Uli Sattler: might not be right point to talk about this, also quite late to include it in this spec Alan Ruttenberg: non-structural constraints are in the current work?

Uli Sattler: some work can be done, but not really to change it all now

Alan Ruttenberg: nothing to do on this now...

PROPOSED: Consider Issue 22 formally closed as postponed

RESOLVED: Consider Issue 22 formally closed as postponed

Issue 57 - Errata in OWL 1.0 documents

Alan Ruttenberg: some errors spotted in OWL doc, since they are not worked on, we should close or postpone this

Alan Ruttenberg: suggests postponing

Jeremy Carroll: probably postpone is better

Evan Wallace: postpone is better

Bijan Parsia: None of the errors show up in OWL2 yes?

Alan Ruttenberg: strawpoll on postpone vs. close

Alan Ruttenberg: let's close it then

PROPOSED: Issue 57 Errata in OWL 1.0 documents closed as moot (not relevant)

RESOLVED: Issue 57 Errata in OWL 1.0 documents closed as moot (not relevant)

Issue 106 OWL 2 namespace per proposal

Alan Ruttenberg: what about namespaces? we keep old one, so OWL2 has the same namespace as the old OWL...

Boris Motik: when we mention namespaces, are we talking about RDF only or also about XML?

Alan Ruttenberg: only about RDF

PROPOSED: Resolve Issue 57 by saying that new OWL 2 vocabulary goes in old OWL 1 namespace

ACCEPTED: Resolve Issue 57 by saying that new OWL 2 vocabulary goes in old OWL 1 namespace

Issue 63 Defining an RDFS compatible semantics

Alan Ruttenberg: not sure if to accept this as a real issue

Alan Ruttenberg: should we close it as completed?

PROPOSED: Close Issue 63 as done.

ACCEPTED: Close Issue 63 as done.

Issue Discussions

Issue 119 Russel paradox in OWL Full due to self restrictions.

Alan Ruttenberg: this is an OWL Full comprehension issue

Jeremy Carroll: to members of previous OWLWG, whether there is new evidence to reconsider comprehension principle?

Peter Patel-Schneider: relationship between DL and Full needs rethink...

Peter Patel-Schneider: ...if comprehension principles go away

Alan Ruttenberg: what do we lose if we go the way Jeremy proposed?

Jeremy Carroll: deleting all comprehension principles allows us to rethink all relations, theoretically good and interesting, but practically that might not be valuable?

Peter Patel-Schneider: one can do a patch to keep things the same...

Peter Patel-Schneider: that might be adequate

Alan Ruttenberg: action on Peter or Ian?

Ian Horrocks: agrees with Peter, needs convincing that we should completely revise OWL Full semantics

Ian Horrocks: this might be closed to "out of scope" w.r.t. our charter

Bijan Parsia: wouldn't mind a new owl full, whether we can agree on the new version is a different issue

Alan Ruttenberg: someone should coordinate, sheperd the patching process

ACTION: IanH to sheperd/coordinate the patching process (per Issue 119)

Issue 97 Add GRDDL to OWL/XML Syntax

Alan Ruttenberg: anyone willing to take this issue?

Bijan Parsia: wants to say a thing on GRDDL

Jeremy Carroll: thinks we need the XSLT

Bijan Parsia: this seems to be almost editorial, depends on what level we are looking at this...

Bijan Parsia: there might be issue with going only for XSLT transformations

Alan Ruttenberg: this is a new information; why don't we ...

Alan Ruttenberg: ...discuss it later when there are others like Ivan and Sandro

Jeremy Carroll: we may get into maintenance problem; can clearly state that text is normative

Bijan Parsia: with OWL API we already have pretty reliable implementation, no point in preferring one implementation or that it should be part of OWLWG deliverables

Bijan Parsia: OWL API tracks the OWL2 spec

Alan Ruttenberg: my concern was satisfied with GRDDL; the main thing now is an easy, compatible translation

Bijan Parsia: there was supposed to be spec and then possibly different implementations?

Jeremy Carroll: GRDDL addresses how to do transformation from XSLT 1

Jeremy Carroll: that was recommended

Alan Ruttenberg: there is a trick, if you want to create a transformation into a language, create a trivial XSLT that replaces the output with the translation... can be done

ACTION: alanr to explore whether a simple transformation via XSLT would work in this case and to show trick for how to *generate* an XSLT to create a GRDDL transform

Issue 111 - User intent signalling

Alan Ruttenberg: would be good to allow users to signal, flag that ontology should be interpreted as OWL1, DL, etc.

Alan Ruttenberg: in the past MIME type was rejected

Alan Ruttenberg: Sandro put an initial email, any comments?

Boris Motik: idea was good, we need to include in the doc a switch to use given OWL semantics

Boris Motik: given RDF doc, we need to see under what OWL it is interpreted (DL, Full,...)

Boris Motik: maybe we don't need a switch per each profile

Jeremy Carroll: correction - MIME wasn't rejected in principle, just because there was no time

Alan Ruttenberg: from notes - this was not needed at the time

--> Bijan Parsia: one problem with MIME - tends not to work offline

Bijan Parsia: not robust enough

Bijan Parsia: for profiles - one reason for including is that people may want to signal that a mixed ontology is interpreted in appropriate way (say DL)

Bijan Parsia: not necessary to disambiguate semantics, but good to flag if users want to emphasize

Alan Ruttenberg: what happens when doing imports and there are different intents in different files

Sandro Hawke: mentioned in email, but no good answer

Sandro Hawke: not sure anybody knows how to implement certain combinations = may need to ban certain combinations?

Alan Ruttenberg: in solving this issue, we need to discuss and know what is the behavior

Jeremy Carroll: maybe we should have no semantics involved here, just graph (?)

Jeremy Carroll: to understand triples if we want to have just a graph, you can't use RDF semantics, as graph has no semantics

Bijan Parsia: Ok, in case of incompatible profiles, then a warning to the user should be signaled and the user offered a choice of which semantics to use

Alan Ruttenberg: kind of like intended semantics RDF entailment

Alan Ruttenberg: specific suggestions from bijan, sandro, jeremy? discuss on email and come back with revised proposal

Alan Ruttenberg: out of time... on this section and discussion

General discussion: Easy keys

Evan Wallace: Is the top property discussion postponed?

Uli Sattler: in the easy keys proposals we described a few things more explicit

Uli Sattler: semantics more explicit, explained why "easy", why this would cause problems

Bijan Parsia: there is one raised, open issue - depends on what we do about keys and b-nodes (?)... if variables can't go with easy keys

Alan Ruttenberg: can you collect situations we are trying to accomplish here?

Bijan Parsia: those will be included on easy keys page

Boris Motik: spoke to uli and got explanations, so no more reservations left

Alan Ruttenberg: we don't have Achille and Zhe - implementers and their position on this

Bijan Parsia: the intent of easy keys was to make it easy for implementation; unless they start messing with datatypes

Bijan Parsia: should work with anything that follows datalog rules

Alan Ruttenberg: bijan can you add a note about the case you worry about or explain it

Bijan Parsia: when you thing about dl-safe rules and datalog, you may not have some things (e.g. negation) in the right place, maybe boris, uli can tell more

Bijan Parsia: if you have finite datatypes you may have more work to do

Alan Ruttenberg: Jeremy is also among implementers - any issues?

Alan Ruttenberg: would be good to have affirmative responses from three implementers so that we can report on this

Alan Ruttenberg: action is needed on this

Alan Ruttenberg: ...would be good getting response from all implementers on the WG

ACTION: alan will get responses from Achille, Zhe, Jeremy as implementors - review of Easy Keys proposal

Alan Ruttenberg: other comments on easy keys or a straw poll?

Alan Ruttenberg: should we go ahead and have this feature added?

Alan Ruttenberg: strawpoll - are we ready to add this to spec

NONBINDING-PROPOSED: Are we ready to include EasyKeys to OWL specification?

Alan Ruttenberg: looks good, good work from bijan and uli to have proposal in such a good shape

Alan Ruttenberg: back to issue list

Alan Ruttenberg: more discussion on any previous issues

Issue Discussions (continued)

Issue 71 - Data ranges for literals with Language

Alan Ruttenberg: Jeremy not here, anybody has opinions on this - should we be handling XML literals as well?

Bijan Parsia: some variant on extending datatype language is fine, to do it somehow - may be useful

Bijan Parsia: XML literals are a bit dodgy - there is some form of inheritance... we should not support this, we don't support many other XML subtyping, because they are a hard problem

Bijan Parsia: go for a middle ground

Peter Patel-Schneider: suggests facet for this purpose

Peter Patel-Schneider: you don't have to impose syntax...

Alan Ruttenberg: will you write something for spec how this may look?

Peter Patel-Schneider: response sent to jeremy, may contain enough info

Alan Ruttenberg: jeremy was suggesting wildcarding? is that covered?

Alan Ruttenberg: e.g. EN* not necessarily, EN-GB EN-US

Bijan Parsia: if we want this from scratch, we can represent this using schema - string + values (facets can go into string part)

Bijan Parsia: this is not a fundamentally difficult thing, just needs to be in a neat way

Bijan Parsia: we should be able to search, cluster strings and in principle it's about having pattern facets

Alan Ruttenberg: what is the status of this right now?

Alan Ruttenberg: will it be easier to use patterns? bijan, will you spec ideas?

Alan Ruttenberg: other comments?

ACTION: Bijan to work out syntax for langed literals

Issue 112 Top property

Alan Ruttenberg: someone who understands "top" property to update us

Uli Sattler: we were unsure how to call it, but for some reason we needed "bottom" role, there was some discussion on universality

Uli Sattler: reasoners can get away with faking this

Alan Ruttenberg: bottom role - when debugging ontologies, one thing that came with unsatisfiable roles was that it could not have any values - could this be equivalent to a bottom role (e.g. maxCard 0)

Uli Sattler: might be a way to fake implementing bottom properties

Uli Sattler: maybe this needs syntactic sugar to name this

Alan Ruttenberg: would this add burden to reasoners?

Uli Sattler: not really, reasoners can handle this

Alan Ruttenberg: what the name should be?

Alan Ruttenberg: there are few possibilities, anybody?

Uli Sattler: some in the email posted recently...

Uli Sattler: should mirror owl:thing

Uli Sattler: "relatesTo" implies meaning which it doesn't really have

Alan Ruttenberg: the usual way to read properties is like a sentence - A topproperty B... sounds like relation between them

Uli Sattler: topProperty should related every individual with every other individual

Uli Sattler: "relatesTo" may be too ambiguous

Alan Ruttenberg: no problems with this

Alan Ruttenberg: strawpoll on adding top and bottom roles to OWL 2

NONBINDING-PROPOSED: Add "top" and "bottom" by some name, to OWL 2 specification?

Alan Ruttenberg: we have good sentiment that this is worth adding, let's discuss the actual names on email

Alan Ruttenberg: one last thing

Alan Ruttenberg: where we are going on whether there should be 1 or 2 OWL semantics documents...

Alan Ruttenberg: should there be one or separate

Alan Ruttenberg: adjourned