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Teleconference.2008.01.30/Minutes
These minutes have been approved by the Working Group and are now protected from editing. (See IRC log of approval discussion.)
See also: IRC log
Contents
- Present
- Achille Fokoue, Bijan Parsia, Boris Motik, Michael Schneider, Rinke Hoekstra, Ivan Herman, Uli Sattler, Ian Horrocks, Carsten Lutz, Peter Patel-Schneider, Michael Smith, Doug Lenat, Evan Wallace, Bernardo Cuenca Grau, James Hendler, Zhe Wu, Ratnesh Sahay, Martin Dzbor, Jeff Pan, Alan Ruttenberg, Deborah McGuinness, Sandro Hawke, Jeremy Carroll
- Regrets
- Vipul Kashyap, Markus Krötzsch
- Chair
- Ian Horrocks
- Scribe
- Bernardo Cuenca Grau
(Scribe changed to Bernardo Cuenca Grau)
Admin
Ian Horrocks: Agenda amendments?
Ian Horrocks: No amendments, accept previous minutes?
Ian Horrocks: minutes approved
RESOLVED: approve previous minutes http://www.w3.org/2007/OWL/wiki/Teleconference.2008.01.23/Minutes
Pending Actions
Ian Horrocks: pending actions
Ian Horrocks: Action 54 complete
Ian Horrocks: people should speak up if they think an action is not completed
Carsten Lutz: the action requested the definition of OWLPrime
Carsten Lutz: not clear what OWL Prime we should discuss
The document is the starting point for discussing OWL Prime
Carsten Lutz: for defining OWL Prime we still need some work
Ian Horrocks (guest): Action 67
Ian Horrocks: Action 71, Boris completed
Ian Horrocks: Action 74, dealt with by Jeremy
Ian Horrocks: Action 90: no agreement for acceptance
Ian Horrocks: Action 90 is ongoing
Ian Horrocks: rich annotations action, any progress?
Bijan Parsia: yes
Alan Ruttenberg: action not yet completed
Ian Horrocks: use case for punning; postponed for next week
Ian Horrocks: Action 72, to be continued
Ian Horrocks: UML association; completed
Ian Horrocks: No proposals to resolve issues; more time for discussion
Discussion on Fragments
Ian Horrocks: fragments and conformance issues
Alan Ruttenberg: at the workshop we achieved a consensus
Alan Ruttenberg: we call fragments to syntax fragments and semantic fragments we called them conformance levels
Ian Horrocks: we agree that the email I sent is a reasonable starting point
Ian Horrocks: Do people understand the difference between fragments and conformance levels?
Carsten Lutz: happy with the distinction, but not clear what a conformance level is
Alan Ruttenberg: we could have a reasoner that does incomplete reasoning, but complete up to a certain set of entailments
James Hendler: we have a very tight definition of language fragments
James Hendler: a fragment could be rather seen as a set of figures that could be supported
Uli Sattler: having conformance levels might be a good idea
Uli Sattler: it gives an idea of what it means to cover a certain construct
Uli Sattler: not too difficult to come up with a definition of conformance level
Uli Sattler: what it means to be correct or complete for a certain class of queries
Zhe Wu: are we going to provide a set of test cases and ensure that implementations should cover them?
Zhe Wu: does this relate to conformance?
Ian Horrocks: My assumption was that we would not define conformance in terms of test cases, but rather something more precise
Sandro Hawke: OWL does have test cases
Sandro Hawke: most standards in industry talk about what a language does
Sandro Hawke: OWL does not specify what a classifier should do
Sandro Hawke: we should come up with a way of defining what a software does
Sandro Hawke: I push for conformance levels
Carsten Lutz: conformance level can be related to PD* semantics
Michael Smith: I wouldn't be confortable specifying fragments without taking into account the proper semantics
Alan Ruttenberg: W3C does validation, and that could be done using tests
James Hendler: take sameAs
James Hendler: has a precise semantics and an RDF match
James Hendler: we should tell the implementors what features they should implement
James Hendler: I'd like a fragment to be defined as a set of language features
James Hendler: one could implement OWL DL features but not following the DL semantics
Bijan Parsia: I do not know what validation is
Bijan Parsia: defining a set of test cases would not be a suitable kind of validation
Zhe Wu: I have discussed about EL++ and Dl-Lite and DLP
Zhe Wu: DLP fits better with rules than EL++ or DL Lite
Zhe Wu: I like DLP better
Zhe Wu: Either PD* semantics or DLP would work in principle
Carsten Lutz: I can see two conditions relevant for a fragment: they should provide useful expressivity, and they should be based in some principle that guides the design, such as tractability of subsumption or horness
Carsten Lutz: What would be the guiding design principle of OWL Prime
Boris Motik: DLP allows to reason about the domain that consists only of the resources that one has in the KB
Boris Motik: no need to generate anonymous individuals
Boris Motik: OWL Prime is pretty close to DLP
Boris Motik: the guiding principle behind DLP is similar to OWL Prime's goals of using rules for reasoning
Boris Motik: wouldn't be difficult to align DLP and OWL Prime
Boris Motik: OWL prime could be seen as an RDF-oriented version of DLP
Zhe Wu: I agree with Boris
Zhe Wu: should be feasible to map OWL Prime to DLP
Zhe Wu: the criteria in Oracle's mind is to meet the requirements of the users
Zhe Wu: it has to allow an efficient implementation in the context of enterprise applications
Zhe Wu: we like rule sin Oracle because they can be implemented efficiently using DBs
agreed
Peter Patel-Schneider: it puts me in an uncomfortable situation
Alan Ruttenberg: the names should be mentioned but the members of the WG should not mention them publicly
James Hendler: Tarlick, Radar Networks and Meta Web have given me details about their specifiic needs
James Hendler: they think that OWL Prime meets their use cases
James Hendler: these companiens would rather not comment in public
James Hendler: we should take into account the needs of those companies
Alan Ruttenberg: could you say something more about OWL prime meeting their needs?
Alan Ruttenberg: is it about syntax?
Alan Ruttenberg: do they care about completeness?
James Hendler: I cannot answer
Alan Ruttenberg: the problem is that I do not know what they mean.
Ian Horrocks: no need to go any further
James Hendler: they prefer scaling rather than completeness
Ian Horrocks: we need to agree what to do next with OWL Prime
Ian Horrocks: what are the next steps?
Zhe Wu: we should come up with a set of DLP rules that characterize OWL Prime
Zhe Wu: these rules would define the semantics
Boris Motik: I agree we should come up with a rule set
Boris Motik: assume an EL ontology which is DLP
Boris Motik: you turn it into RDF
Boris Motik: and then run the rules
Boris Motik: and obtain the same answers
James Hendler: we may have both fragments and conformance levels
James Hendler: there's technical issues that differentiate a full subset from a DLP subset
James Hendler: define a fragment as a subset of a vocabulary and the semantics is the OWL Full semantics
James Hendler: but I think there could also be a DL version
ACTION: jeremy to arrange HP review of OWL Prime page
Alan Ruttenberg: I want to meke clear what is the treatment of non-answers
Alan Ruttenberg: I understand that rule systems do not put constraints in the use of classes in the place of instances and vice-versa
Alan Ruttenberg: this does not seem to be in DLP
Boris Motik: I think that DLP and OWL prime could really be made equivalent
Boris Motik: OWL Prime is OWL Full like, and we should generate some restrictions
Michael Smith: HP should better spend resources later on, when the spec is more advanced
James Hendler: I don't want to move to closed-world semantics
Ian Horrocks: the fragment as specified is decidable
James Hendler: I don't mind if there is a DL version of the fragment, but there should be an OWl Prime Full
James Hendler: I am fine with OWL Prime DL being DLP
James Hendler: as long as there is also a Full version
Boris Motik: ther eis no CWA in DLP, nor there is a domain closure assumption
Boris Motik: what happens is that the use of existentials in the language is limited
Ian Horrocks: as I understand conformance level is that it gives you the entailments that should be inferred
Ian Horrocks: it specifies a minimum but not an upper bound
Boris Motik: for certain kinds of queries the answers between DLp and OWLPrime (the rdf version of DLP), the answers should be the same
Boris Motik: I am talking about entailments and non-entailments
James Hendler: most languages I have encountered are defined in terms of rules
James Hendler: but this is not the case in this WG
James Hendler: we should have an axiomatic semantics
Boris Motik: DLs are closer to FOL in that nothing is reified
Boris Motik: so the theory is the ontology
Boris Motik: in the case of OWL Full and OWL Prime, you ahve a set of axioms that reify your theory
Boris Motik: the equivalence between DLP and OWL Prime could be established
Boris Motik: for a certain kind of entailments
Boris Motik: those that make sense in DLs
Ian Horrocks: next item in the agenda
James Hendler: Boris won an award, congrats
Issues
ACTION: bmotik to Send an e-mail to the list with ideas on how to bridge DLP and OWL Prime
Ian Horrocks: resolved
ACTION: bmotik2 to Send an e-mail to the list with ideas on how to bridge DLP and OWL Prime
Ian Horrocks: entity annotations? should we have annotations in entity declarations?
Peter Patel-Schneider: I proposed to decrease the kinds of annotations allowed
Boris Motik: there is another asymmetry
Boris Motik: annotations of axioms are not axioms themselves
Boris Motik: this causes an asymmetry
Boris Motik: Matthew suggested to make all annotations axioms
Alan Ruttenberg: do annotations become domain elements?
Boris Motik: all this is purely syntactic
Boris Motik: we could put annotations on ontologies, entities and axioms
Washington Face to Face
Ian Horrocks: peter requested to ask for sponsorship for OWLEd
IanH and alan: we endorse the request
Peter Patel-Schneider: we would like to get enough money so that we do not need registration fees
Ian Horrocks: there is an issue concerning observers in the next F2F
Ian Horrocks: we had some issues with observers in manchester
Ivan Herman: we mean observers from member organizations, right?
Ian Horrocks: it would be possible to have observers from non members, but
Ian Horrocks: they may be asked to leave the room
Bijan Parsia: I do not believe there are issues with non-members
Imports Task Force
Alan Ruttenberg: the imports task force meeting is next monday