F2F1 Minutes Session 6

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Part of F2F1 Minutes.

OWL Working Group Meeting Minutes, 07 December 2007

DRAFT. Currently Under Review

See also: IRC log


Scribe
Evan Wallace


Ian Horrocks: We now have Zakim connected for those who want to dial in.

OWL DL and OWL Full

Slides for this session: Media:pfps-f2f1.pdf (pp. 1-3)

Peter presenting


Here's a brief description of how model theoretic semantics works

Peter Patel-Schneider: OWL DL has a fairly straightforward take on this

Peter Patel-Schneider: OWL Full and RDF take a slightly weird take on this

Peter Patel-Schneider: wherein properties and classes live in the world with real objects

Peter Patel-Schneider: Here are the differences between OWL DL and Full semantics

See "Two Model Theories" slide

Peter Patel-Schneider: things like rdf:type and owl:Class are not in the world in DL but are in Full

Alan Ruttenberg: In OWL DL Universe what is the status of Ontologies?

Peter Patel-Schneider: There is a separate place for them because of annotations

Peter Patel-Schneider: This description is about the specification and not practice

Bijan Parsia: The things in the OWL Full universe are in there with a theory

Peter Patel-Schneider: None of this matters in some sense

Peter Patel-Schneider: What matters is the behavior which results

Peter Patel-Schneider: ...such as entailments

Peter Patel-Schneider: Differences: It's possible to make assertions about the OWL vocabulary that change their interpretation

Slides for the rest of this session: Media:carroll-f2f1.pdf

Jeremy to take over presenting

Alan Ruttenberg: question about the intention of compatibility to be entailments of DL and Full be identical

Jeremy Carroll: for me the whole point is to get compatibility with RDF

Jeremy Carroll: A goal is "least surprise" for users of RDF when using OWL

Jeremy Carroll: OWL annotations are intended to behave as RDF annotations

Alan Ruttenberg: There are implications for RDF annotations that users may not be aware of

Alan Ruttenberg: I want to make a distinction between usage and consequences of the semantics

Bijan Parsia: I don't understand what you mean by RDF triple-by-triple semantics

Jeremy Carroll: In the OWL 1.0 semantics there are correspondence theorems between OWL Full and DL Semantics

Jeremy listed Issues related to the FULL and DL differences

such as 63, 76, 81, 69, 72, 55, 73

Jeremy Carroll: Do we want to allow semantic subsetting for fragments

Bijan Parsia: If we are going to support OWL Full do we need to support the full RDF umbrella

Joanne Luciano: He said something about if he wanted to reproduce what is in Jena, he'd like to have that info available to know what to reproduce

Bijan Parsia: described in Jeremy presentation

Jeremy Carroll: The semantic of RDF reification are essentially none

Bijan Parsia: There exists somewhere in the known universe a Statement that includes: S, P, O

Jeremy Carroll: There is no clear statement in the specs for how reification can work interoperably from system to system

Bijan Parsia: In the OWL full situation you have to interpret the reification syntax somehow

More discussion about how this can be done

Jeremy Carroll: Punning

In some peoples mind the web arch specifies that a URI corresponds to a single meaning

Punning is weaker than OWL Full because it violates this principle

Jeremy Carroll: this seems to cause user confusion

Mapping rules

In my view, the mapping rules were the hardest part of the OWL Rec

Jeremy Carroll: The drivers behind the mapping rules in OWL 1.1 are different

Jeremy Carroll: ...and this will lead to considerable change and probably

Boris Motik is speaking

Jeremy Carroll: ...issues later on.

Boris Motik: In my opinion many of these problems are the result of

Boris Motik: ...shoe-horning everything in the same universe.

Point for discussion later:

Joanne Luciano: please distribute (and reference here for later). which sldie # of URI / slide ref
Joanne Luciano: \me Thanks Peter.

Boris Motik: if we came up with an OWL Full that has a clean model theoritic framework

...then we could fix this.

Alan Ruttenberg: This would be a smaller OWL Full?

Bijan Parsia: Punning was intended to meet the goals of Full at least quarter way

Peter Patel-Schneider: The dogma in this case is the same syntax extension of RDF

Bernardo Cuenca Grau: The people who like OWL Full should really come up

...with features for OWL Full that they like and use

...Then we could do some research.

Ian Horrocks: The point I wanted to make was how much of this proposed

...work will be part of the work of this WG?

Boris Motik: Cleaning this up would be a huge accomplishment for this group.

Alan Ruttenberg: To my mind, it's not clear that cleaning up OWL Full is desirable to

... the Full/RDF community.

Jeremy Carroll: Dropping the comprehension principles seems like the

... smallest change that would be of value.

Alan Ruttenberg: Is this in scope for our group? Strictly speaking I don't think so.

Ian Horrocks: This kind of work just isn't in scope.

Bijan Parsia: Form an OWLED task force to look at this.

Alan Ruttenberg: We need to have a discussion about what compatibility means.

Alan Ruttenberg: If we allow OWL Full semantics changing that will affect backwards compatibility

Discussion of semantic fragments

Alan Ruttenberg: we have a delta now in the sublanguage entailments

Bijan Parsia: finding some delta that makes sense that makes the languages

...as close as possible would be a good thing.

Ian Horrocks: If we are comfortable with this semantic subsetting then

... we should be happy with the Full - DL differences

Ian Horrocks: One slight difference in Jeremy's proposal would be allowing

... more syntactic freedom but actually reducing the entailments

... by removing the comprehension principles for e.g.

Jeremy Carroll: HP might be happy with such a result if it is consistent

... with some broader framework.

Jeremy Carroll: There are easy bits in the OWL 1.1 language.

... getting those bits working are a bounded and achievable task.

Bijan Parsia: My experience is that users are concerned about not

... being able to process large numbers of RDF graphs

...with DL reasoners.

... Features like punning improves this situation.

Ian Horrocks: I wonder how hard it would really be to extend the status quo

... with some acceptable differences.

Ian Horrocks: This is a strawman for something that we could do.

Jeremy Carroll: I'd need to take this proposal back to HP before commenting on it.

Bijan Parsia: I would like us to keep the political and the user requirements seperate

ACTION: jeremy describe how punning and cardinality play poorly with each other


Jeremy Carroll: maybe we can say in the spec that punning is a concession to implementors, not a basic part of the semantics, that univocality is intended. [Scribe assist by Sandro Hawke]

Ian Horrocks: I'd like to see suggestions for concrete ways of moving forward to address these problems

Jeremy Carroll: Why don't we start with Qualified Cardinality Description?

Peter Patel-Schneider: Someone made comment that Qualified Cardinality Descriptions leads to non-monitonicity

... and I remember finding it believable

ACTION: pfps inform the WG on absurdity of QCR / OWL Full


ACTION: jeremy attempt Wiki sketch of QCR semantics OWL Full


Alan Ruttenberg: on concrete actions...

Alan Ruttenberg: How about we say: If you manage to game the system to have different meanings for a URI, you can't count on that [Scribe assist by Sandro Hawke]

... we have a set of options

Jeremy Carroll: a suggestion that Jeremy concentrate on OWL Full

... Semantics and drop out of User Facing Documents

Alan Ruttenberg: Any other specific proposals?

Ian Horrocks: Let's try and extend where are now and see where we end up.

Alan Ruttenberg: When do we evaluate when this approach is failing

... so that we can try another approach?

... I want to have some ideas about where we would go if this

... doesn't work.

Jeremy Carroll: We have had two variants proposed today.

... Sacrifice backwards compatibility and work towards 1.1

Bijan Parsia: We are spending a lot of time on this.

... I would like to know how much interest in this WG

... with Full compatibility.

Sandro Hawke: If there were a task force, who would be on it? -- Alan, Jeremy, Sandro
Jeremy Carroll: variant 2 - peter - drop same syntax requirement, and allow OWL 1.1 DL to have different syntax from RDF [Scribe assist by Jeremy Carroll]

Stawpoll

How many people want to use OWL Full for 1.1?

Joanne Luciano: 2nd question... +1 (not listed yet)

Jeremy rephrase: When using 1.1 do you want to use Full semantics?

Sandro Hawke: Q1- Are you a potential customer for OWL 1.1 Full -- you'll be using the document
Sandro Hawke: customer or reseller
Joanne Luciano: Q1 No.

Q1:

5 yes in room
15 no
Deborah McGuinness: jim would also be in the positive count for that question

q2 Are you a potential customer for Bijan's description of patch-up rules?

Sandro Hawke: Q2- Are you a potential customer/reseller of a specification of techniques for translation RDF graphs (in the spirit of OWL Full) to OWL 1.1 DL
Sandro Hawke: Q2- Are you a potential customer/reseller of a specification of techniques for translating RDF graphs (in the spirit of OWL Full) to OWL 1.1 DL
Joanne Luciano: Q2 yes
Joanne Luciano: Q2 +1

many in favor

Sandro Hawke: Q2 yes except for 2 abstainers