F2F1 Minutes

Achille Fokoue: +1

Zhe Wu: +1

Jeremy Carroll: http://lists.w3.org/Archives/Public/public-owl-wg/2007Dec/att-0080/UFDTF_overview2.pdf

Sandro Hawke: rerun -- not counting observers....

in favor 14 (including the 3 remote participants)

against - pfps, sandro, alanrut - 3 total

abstain - hp

we could consider adding a swrl extension syntax to this proposal

Alan Ruttenberg: this may be out of scope

Joanne Luciano: Please note - I have to get on another conf call at 1630; I will monitor the call, but announce loudly if you move to Testing. I want to participate in that discussion if possible.

Joanne Luciano: Monitor via the chat - need the phone for th eother conf call.

Sandro Hawke: Add a hook for user-defined extensions.

s/Add/Boris (guest): Add/ [Scribe assist by Sandro Hawke]

feedback that it is reasonable to continue developing this

Joanne Luciano: still on chat though!

Alan Ruttenberg: What worries me is that you can have an OWL document that doesn't look like an OWL document. [Scribe assist by Sandro Hawke]

(Scribe changed to Giorgos Stoilos)

User Facing Documents

Slides for this session: Media:wallace-f2f1.pdf

Evan wallace is presenting the status of User Facing Documents

...documents that will help users into owl 1.1

...like guide, overview, reference

Evan Wallace: work mainly volunteered

...should these documents be produced as part of the spec?

...what syntax to use for the examples, different users have different preferences...DL syntax

...abstract syntax, etc

Evan Wallace: e.g. some docs use the DL side, while others use, like the Reference use a Semantic Web side (meaning RDF)

no much progress has been done

uli2 (guest): My (unfinished) tutorial with multiple syntaxes inline: http://www.cs.man.ac.uk/~bparsia/2007/owltutorial/

preference in producing an overview doc that is between OWL 1.1 overview and OWL overview

Sandro Hawke: (rather contovercially) I hope the Semantic Web survives RDF. [ That is, the goals of Semantic Web are important. RDF may not be the best way to meet those goals. I hope those goals are met, even if it mean moving beyond RDF. ] [Scribe assist by Sandro Hawke]

Deborah McGuinness: looking at the overview for 1.0, http://www.w3.org/TR/owl-features/

Bijan Parsia: is working in a way to choose to preview an example in the syntax of your choice

Deborah McGuinness: that overview suggestion might be drop section 1, and drop it from organizing section 2

Deborah McGuinness: looked in OWL 1.1 overview

Jeremy Carroll: a question is how much of the old docs we will use or start new ones

Deborah McGuinness: my comments were on starting from owl 1.0 overview

Deborah McGuinness: (and integrating in the owl 1.1 overview diff info)

Jeremy Carroll: do we want to extend the owl1.0 docs?

Bijan Parsia: oposes to extending the owl 1.0 docs. Finds them confusing

...don't thinks that good "tutorials" could be written within the WG

Bijan Parsia: if people want to go forward then he proposes something like RDF Primer

Ian Horrocks: thinks that an entry doc is very important and usefull

Bijan Parsia: what about the homepage?

...contains motivation, intro, etc

Michael Smith: homepage could also be improved to serve as a better intro doc

Zhe Wu: i'd like to see a doc with a complete list of new vocabularies and pointers to examples and semantics

Alan Ruttenberg: people are not learning OWL from the docs. Use them as refs rather than intros

Joanne Luciano: It would be good to take a poll (if one's not been already) to see objectively how people are learning OWL.

Bijan Parsia: exaplain some problems related to w3c for updating the docs

Bijan Parsia: proposes changing license on old OWL 1.0 UFD to allow derivatives [Scribe assist by Jeremy Carroll]

Bijan Parsia: this would allow (not this WG) to support the old docs (i.e. publish new versions outside this space) [Scribe assist by Jeremy Carroll]

Vipul Kashyap: agrees with alan rut

Vipul Kashyap: would like to have domain specific examples [Scribe assist by Jeremy Carroll]

Vipul Kashyap: how do we decide what goes where W3C or outside? [Scribe assist by Jeremy Carroll]

Bernardo Cuenca Grau: agrees with bijan. Why does educational material go to rec?

Uli Sattler: what about updating old docs with links to new matterial

Deborah McGuinness: don't see how this could be done

Sandro Hawke: explains a way

Vipul Kashyap: Why not?

Vipul Kashyap: I mean why should educational material/use cases/requirements not be part of the rec track?

Vipul Kashyap: I would like some clear guidance and criteria from W3C

Vipul Kashyap: Just forwarded Michel Dumontier's response to the OWL WG mailing list

Alan Ruttenberg: asks for a clarification on sandros example

Jeremy Carroll: RecTrack document means that author gets acknowledgement as W3C Document author, which in turn should mean more commitment towards the work. [Scribe assist by Pascal Hitzler]

Deborah McGuinness: +1

Evan Wallace: a plain language doc that could be used by non-experts is very good

Vipul Kashyap: Jeremy's response is "content independent"

Vipul Kashyap: Doesn't help me decide either way

Bijan Parsia: I am not highly against rectrack docs but more in favour for notes

Ian Horrocks: put the rectrack non-rectrack aside and think about the docs

Ian Horrocks: it seems from today that overall docs are not very good

Ian Horrocks: come again to the question whether starting fresh docs or extending old ones

Ivan Herman: has found guide docs of various groups very helpfull, like XML schema

Ivan Herman: if these docs have the blessing of the group then this is much better

....producing similar docs for the community would be good

Alan Ruttenberg: do we agree that we need a reference doc

Achille Fokoue: +1

Uli Sattler: ivan, if they are notes, they will still have the blessing of the WG?

Deborah McGuinness: because there are problems with existing ones does not mean we have to start with new ones

Bijan Parsia: proposes a fresh "primer" doc as a replacement of overview and guide

PROPOSED: To meet our charter deliverable of covering the intent of 'Overview' and 'Guide', we'll publish a new 'Primer' (written largely from scratch).

Joanne Luciano: +1 I like the primer idea

Joanne Luciano: How do we evaluate what we do (in general)?

James Hendler: asks about where the specification of OWL Full would go. Does not see it in OWL 1.1. functional syntax

Jeremy Carroll: agrees with jim. It would be helpfull to have a doc which explains to non-experts features of owl full

Evan Wallace: test

James Hendler: gives an example of inverseFunctional DatatypeProperties [Scribe assist by Giorgos Stoilos]

Jeremy Carroll: http://www.w3.org/TR/owl-ref/#InverseFunctionalProperty-def

Jeremy Carroll: jim's question is where would such text go if we do not have a document like OWL Reference

particularly (guest): [Scribe assist by Jeremy Carroll]

NOTE (guest): Because in OWL Full datatype properties are a subclass of object properties, an inverse-functional property can be defined for datatype properties. In OWL DL object properties and datatype properties are disjoint, so an inverse-functional property cannot be defined for datatype properties. See also Sec. 8.1 and Sec. 8.2. [Scribe assist by Jeremy Carroll]

Ian Horrocks: maybe we will decide to have such a documents (like the reference) [Scribe assist by Giorgos Stoilos]

Bijan Parsia: functional syntax must not change since it is the formal specification

PROPOSED: To meet our charter deliverable of covering the intent of 'Overview' and 'Guide', we'll publish a new 'Primer' (written largely from scratch).

Jeremy Carroll: To meet our charter deliverable of covering the intent of 'Overview' we'll work from OWL OVerview 1.0

Jeremy Carroll: To meet our charter deliverable of covering the intent of 'Guide', we'll publish a new 'Guide'

Jeremy Carroll: To meet our charter deliverable of covering the intent of 'Guide', we'll work from OWL Guide 1.0

Vipul Kashyap: I need a clarification

James Hendler: (can each of the things we are being asked to strawpole on be put up one at a time? - and I cannot see IRC from before joining, of course)

Vipul Kashyap: Perhaps working towards a document set like:

Vipul Kashyap: An introductory document between OWL 1.1 Overview and OWL Overview from Rec. (without the species of OWL emphasis)

Vipul Kashyap: A document intended as a language reference written in plain english

PROPOSED-1 (guest): To meet our charter deliverable of covering the intent of 'Overview' and 'Guide', we'll publish a new 'Primer' (written largely from scratch). [Scribe assist by Sandro Hawke]

Vipul Kashyap: Requirements with traceability

PROPOSED-2 (guest): To meet our charter deliverable of covering the intent of 'Overview' we'll work from OWL OVerview 1.0 [Scribe assist by Sandro Hawke]

Jeremy Carroll: no not really (to jim)

Peter Patel-Schneider: Aparently we should have 3 proposals: i) old docs, ii) fresh docs iii) prime proposal (bijan's)

James Hendler: wish I'd joined call earlier - incremental seems a lot less work than starting from scratch

PROPOSED: Refresh the old documents (otherwise, start mostly from scratch).

straw poll: YES=refresh docs NO=start new ones.

James Hendler: but no way to say yes to some docs and no to others? shouldn't we do this doc by doc?

Ian Horrocks: lets go doc by doc

Vipul Kashyap: Forwarded Christine's response to the OWL WG

straw poll on =overview=

James Hendler: overview = YES

PROPOSED: 'Overview' requirement from charter to be met by cleaned up and expanded-as-needed version of 2004 OWL Overview

James Hendler: +1

Zhe Wu: +1 (like to see delta)

Vipul Kashyap: +1

Joanne Luciano: 0 (just rejoined)

Sandro Hawke: pro in room - 4

Vipul Kashyap: +1 to start from scratch

votes for no in room - 9

Sandro Hawke: con in room - 9

Ian Horrocks: essentially a tie.... [Scribe assist by Sandro Hawke]

James Hendler: I VOTE YES

Ian Horrocks: people from the call are confused on what YES/NO choices meant. New poll is performed

Zhe Wu: +1

count on room: 3

Vipul Kashyap: +1 for NO

total for yes: 7

Achille Fokoue: abstain

votes for no=12 (11 + vipul)

Vipul Kashyap: OK

Vipul Kashyap: -1 then

PROPOSED: 'Requirements' requirement from charter to be met by cleaned up and expanded-as-needed version of 2004 OWL publication

next doc to poll =requirements=

voting for yes:

Ian Horrocks: Yes mean keep current document and warm it up. [Scribe assist by Sandro Hawke]

Zhe Wu: 0

Vipul Kashyap: -1

count on the room: 2

James Hendler: -1

voting for no

Elisa Kendall: -1

Joanne Luciano: +1 voitn for no

room (guest): 12

James Hendler: so it's not just the phone that is confused :-)

PROPOSED: 'Formal Specification' requirement from charter to be met by cleaned up and expanded-as-needed version of 2004 OWL publication

next doc =Reference=

James Hendler: +1 for reference

Starting vote from YES

Zhe Wu: +1

PROPOSED: 'Descriptive Specification requirement from charter to be met by cleaned up and expanded-as-needed version of 2004 OWL publication

Sandro Hawke: (skipping Formal Spec because it's not user facing)

count yes (refresh) in the room: 4

voting for no

Joanne Luciano: +1 start fresh

Vipul Kashyap: -1

count in room for no: 13

PROPOSED: 'GUIDE requirement from charter to be met by cleaned up and expanded-as-needed version of 2004 OWL publication

James Hendler: +1 yes for Guide

Sandro Hawke: http://www.w3.org/2007/OWL/wiki/Test_Case_Experiment

voting for yes:

Zhe Wu: +1

room for yes: 2

Vipul Kashyap: -1

voting for no

Joanne Luciano: +1 do new!

room for no: 13

James Hendler: but this means we cannot do incremental?

Peter Patel-Schneider: rough "page size" for Overview 14 - Reference 50 - Guide 38

Deborah McGuinness: An introductory document between OWL 1.1 Overview and OWL Overview from Rec. (without the species of OWL emphasis)

Deborah McGuinness: from evan

Vipul Kashyap: +1

Ian Horrocks: maybe not have a poll on evan's suggestion (above) since it is currently not clear

Deborah McGuinness: ha ha from joanne

Joanne Luciano: I want to stay!

test cases

Jeremy Carroll: explains some ways for doing tests

...every feature in the spec must have a test

Joanne Luciano: both are important

Jeremy Carroll: in owl test was a normative doc

Ivan Herman: not in sparql

James Hendler: note that to be able to leave PR, one must document that every feature is implementable, and the tests are a way to do that

James Hendler: +1 to postponing the decision

Ivan Herman: don't need to decide now about normative or non

Alan Ruttenberg: put test cases on wiki

Ian Horrocks: what will happen with existing test, will they be on the wiki

Joanne Luciano: response to alanrec - would have to update the tests!

James Hendler: do we have any commitment on archivability of the wiki?

Sandro Hawke: yes

James Hendler: and can it be frozen so it cannot be changed after some point (i.e. something that goes to Rec shouldn't have a "live document")

Sandro Hawke: test cases on wiki -- Sandro coding, Bijan as user, AlanRut, Jeremy

ACTION: Sandro to develop scripts to extract test cases from wiki, coordinating with Bijan, Jeremey, AlanRut.

Joanne Luciano: do we view test cases as sameas evaluation?

James Hendler: we phone folks just got cut off - meeting room left the wiki...

Jeremy Carroll: (meeting adjourned)

Jeremy Carroll: something went wrong with phone

Sandro Hawke: We got hung up on.....

Zhe Wu: i can hear someone typing

Jeremy Carroll: but we decided to adjourn

Evan Wallace: Zakim was cut off because we went past our scheduled time

Session 5 (Day 2, 09:00 - 10:45)

The text of this section is automatically included from F2F1 Minutes Session 5. Edits should be done there.

(Scribe changed to Jeff Pan)

Alan Ruttenberg: Major issue seems to be whether to use xsd datatype semantics

Datatypes

Slides for this session: Media:sattler-f2f1.pdf

Joanne Luciano: Alanr, let's meet when you get back

Uli is presenting

Joanne Luciano: are we starting with Issue 25 as in the agenda?

OWL DL does not support user defined datatypes

Uli Sattler: users want to represent intervals

... and comparisons

Ian Horrocks: slides available at http://www.cs.man.ac.uk/~horrocks/owl1.1-datatypes.pdf

... in OWL DL no inverse functional datatype properties

... not to mention composite keys (not even OWL Full supports this)

Boris Motik: we might want to keep the unit mapping out of TBox

Jeremy Carroll: second

Sebastian Brandt: there are real world examples

... that we need datatype mapping in the TBox

Bijan Parsia: both needed

Uli Sattler: we have examples of seeing class subsumption checking based on datatype constraints

Carsten Lutz: it is difficult to choose one standard set, e.g. covering integers, rational, +, *, ...

Uli Sattler: as many as possible

Jeremy Carroll: each simple example is easy

... but have concern on having all of them, which makes it hard

Bijan Parsia: Sebatian's use case: http://www.w3.org/2007/OWL/wiki/N-ary_Data_predicate_use_case

Sebastian Brandt: combining DL and data values are important and useful, there are many tasks that you could not solve if you treat datatypes externally

Alan Ruttenberg: do we want to detect the problematic cases?

Joanne Luciano: what does alan mean by "detect"?

Jeff Pan: there are existing works on datatype groups, a mechanism is already there, see http://www.websemanticsjournal.org/papers/20050811/document.pdf

Thomas Schneider: Uli has just added "[Alan] add support to check whether this mechanism (second item of '3.') has been used 'safely'". Does this help?

... even in OWL DL, freely combinations are not possible, e.g. transitive properties are not allowed to used in number restrictions

Alan Ruttenberg: I mean during species validation, for example. Or via declarations of what features are used and flagging incompatible combinations

Jeremy Carroll: what happen if data in the user databases having both integers, rationals + and * ...

Michael Smith: link again http://www.w3.org/2007/OWL/wiki/N-ary_Data_predicate_use_case

Boris Motik: we need some datatype profile

Carsten Lutz: second boris point

Jeff Pan: two points: 1) profiling is a good idea, there have been work there such as datatype groups

... and we could provide a list of feasible datatype groups

2) if users have integers, rationals + and *, we could simply have type promotion, promoting integers into rational, and it is still decidable, see http://www.w3.org/TR/swbp-xsch-datatypes/ and http://www.w3.org/TR/xpath20/#promotion

Alan Ruttenberg: maybe we could have a stroll poll on this

Bijan Parsia: we all agree that some sort of datatypes are needed, no matter in OWL or RIF

... many of our cases cannot be addressed by RIF

Jeremy Carroll: transitive issue is different

Bijan Parsia: linear polynomial (in-)equations over the reals or cardinals with order relations,

Bijan Parsia: nonlinear multivariate polynomial (in-)equations over complex numbers,

Bijan Parsia: (from the racer manual: http://www.sts.tu-harburg.de/~r.f.moeller/racer/racer-manual-1-7-19.pdf )

Bijan Parsia: page 11

Bijan Parsia: See page 47 and 48

Bijan Parsia: e.g., (* real AN ) (AN of type real or complex)

Jeff Pan: besides Racer, an extension of FaCT (FaCT-DG) also supports n-ary and datatype groups

Uli Sattler: we could have some more general proposal, rather than specific ones

Bijan Parsia: we don't have to require all our implementors to implement everything, so we should be flexible somehow

Uli Sattler: the 4th point: easy keys

Markus Krötzsch: in foaf people use b-nodes rather than individuals, so the easy key might not solve the foat problem

Bijan Parsia: What I meant: It's a bad idea to, in committee, to significantly and somewhat arbitrarily increase the implementation burden. But without adding a hook, implementors *can't* (compatibly) experiment

Bijan Parsia: So, let's add the hook and be cautious about how we fill in the hook

stall poll 1: many +1, no -1, four 0

s/stall/straw

straw poll 2: (all) +1

straw poll 3 (about 2-b): many +1, two (conditional) -1, six 0

straw poll 4 (n-ary datatype): twelve +1, six -1, five 0

straw poll 5(easy key): 22 +1, one -1

Boris Motik: one profile proposal: a set of default profiles and allowing users to have arbitrary profiles

Boris Motik: or people would be able to define their own profiles

Another go, boris' profile: a fixed set of profile and also allowing people to define their owl profiles

alanr's proposal: a fixed set of profile

Bijan Parsia: Note the current support for unary datatypes is already fragmenty: http://spreadsheets.google.com/pub?key=pTmcCXR-dV6RpTEPxB0O-DQ

straw poll on profiling on datatype: eighteen +1, four 0

Thomas Schneider: dmitry tsarkov introduced himself ...

Thomas Schneider: ... email: tsarkov@cs.man.ac.uk

scribers should clean up yesterday's minutes by next telecon

(by IanH and no objections)

Session 6 (Day 2, 11:15 - 13:00)

The text of this section is automatically included from F2F1 Minutes Session 6. Edits should be done there.

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

Session 7 (Day 2, 14:00 - 15:45)

The text of this section is automatically included from F2F1 Minutes Session 7. Edits should be done there.

RIF and OWL WG Collaboration

Alan Ruttenberg: there is a proposal to have a joint OWL & RIF task force

Alan Ruttenberg: ... peter is there. is there anyone else?

Alan Ruttenberg: ...uli is a second.

Sandro Hawke: I may sort of be on it for both

Bijan Parsia: I am liason to RIF and will continue to be

Fragments - OWL Prime

Slides were presented by Zhe Wu remotely, using Oracle conferencing software

Slide: Agenda

Slides for this session: Media:zhe-f2f1.pdf

Ian Horrocks: slides just sent to public-... list

Slide: Oracle 10gR2 RDF

Some technical difficulties continued w.r.t slide presentation

Zhe Wu: many ways to insert data.

Zhe Wu: ...in 10r2 we also support some inferencing and rules. we use forward chaining approach

Zhe Wu: ...also query using a SPARQL-like syntax

Zhe Wu: ... this was all in 2005

Slide: 11gR1

Zhe Wu: this year new release with new features. faster loading, owl reasoning with proof generation

Zhe Wu: ... overhauled performance w.r.t. load and query

Zhe Wu: ... just recently added Jena / Oracle adapter

Zhe Wu: ... joint with HP

Slide

Zhe Wu: subset of owl is supported

Uli Sattler: i'm curious about what scalable and efficient means

Zhe Wu: i will show some numbers later

Zhe Wu: ... re: what is supported - forward chaining rules implementation for fast query answer

Slide: "Why?"

Zhe Wu: ... conclusion in ISWC 2006 paper was that existing reasoners had problems with large ABox data

Slide 7: OWL subsets supported

Zhe Wu: rdfs++ added as a "minimal" extension to RDFS

Zhe Wu: ...owl prime, what is now proposed as rdfs 3.0

Slide: semantics characterized by entailment rules

Zhe Wu: owl prime has ~50 rules

Pascal Hitzler: does somebody know the exact literature reference for OWLPrime and can send it?

Pascal Hitzler: similar for OWLSIF - literature reference ...

Thomas Schneider: BTW The pdf with these slides can be found under http://ontolog.cim3.net/file/work/DatabaseAndOntology/2007-10-18_AlanWu/RDBMS-RDFS-OWL-InferenceEngine--AlanWu_20071018.pdf :)

Slide: Applications of partial dl semantics

Bijan Parsia: BTW, the survey paper mentioned in the talk on slide 9 is at: http://www.mindswap.org/papers/2006/survey.pdf

Bijan Parsia: It has more fine grained analyses, including in terms of AL, ALHF, SHIF, and SHOIN, on the one hand, and RDFS(DL), DL-Lite, EL++, and "non-tractable"

Bijan Parsia: It also discusses "repairable" OWL Full ontologies and (sketchily) how the non-repairable ones fall into OWL Full

Bijan Parsia: It's not at all clear to me how to map the analyses in that paper to OWL Prime (in part because I don't understand OWL Prime)

James Hendler: paper also took a DL approach to the world, the raw data showed the great bulk of the stuff out there, pre-change, was low expressivity RDF or RDF with a little OWL - it's where the RDF 3.0 proposal came from

Bijan Parsia: Uhm...I don't knwo what you mean by "raw data" and "great bulk"

Bijan Parsia: In fact, I don't see that anything I said had anything to do with what fell into RDFS or not

Bijan Parsia: The repair had mostly to do with the nominally owl full documents.

Bijan Parsia: In fact, if you look at table 2 and table 3, the second part of your assertion is at least questionable

Bijan Parsia: """Of the 307 OWL Full documents that can be patched, 63% become OWL Lite documents, and just 37% become OWL DL. Two observations can be made. First, The majority (91%) of the OWL Full documents (from Table 2) can be turned into a decideable portions of the languages by adding type triples. Secondly, the majority of RDFS documents (95%) can transition to OWL easily by adding type triples and use OWL vocabulary instead of RDFS vocabulary."""

Slide: support semantics beyond owl prime

Jeremy Carroll: question about example being supported directly in the future

Zhe Wu: exactly

Achille Fokoue: question about updates to abox

Zhe Wu: i'll get to that later

Slide 13: Advanced options

Alan Ruttenberg: question about time, can we focus on questions now

Zhe Wu: ok, i'll quickly browse remaining slides, then go to questions

Slide: implementation in rules

Zhe Wu: I want to stress that we did not handle one property at a time

Zhe Wu: I'll jump to query answering slide

Zhe Wu: ...that's all I wanted to cover, open for questions

Post Presentation Q & A

Ian Horrocks: the tractable fragments doc describes fragments with known database mapping. wondering why you didn't choose one of those

Zhe Wu: we started by asking existing customers what they needed. most told us they just needed simple extension into owl from rdf

Zhe Wu: ... pretty much the approach was driven by customers and need to implement efficiently

Ian Horrocks: but, customers said you needed something small (rdf + a bit) which is exactly what the fragments are. instead you chose a large fragment and implemented incompletely

Zhe Wu: so far, for those other fragments we have not found a complete rule set (except PD*)

Sandro Hawke: (I find the "small fragment" vs "large fragment" language very confusing, because I don't know what the metric is. large number of terms? large number of users? large implementation effort needed?

Bijan Parsia: Expressivity, I think

Uli Sattler: I want to echo ian and point out that you don't allow intersection, but a clever user would have it

Uli Sattler: ...and to be complete complexity becomes a problem

Uli Sattler: Complete with respect to one reasoning problem is sound with respect to another. ( In OWL? Really?? ) [Scribe assist by Sandro Hawke]

Alan Ruttenberg: they're not trying to be complete

Pascal Hitzler: the mentioned paper by ter Horst seems to be the following: Herman J. ter Horst, Completeness, decidability and complexity of entailment for RDF Schema and a semantic extension involving the OWL vocabulary, Web Semantics: Science, Services and Agents on the World Wide WebVolume 3, Issues 2-3, , Selcted Papers from the International Semantic Web Conference, 2004 - ISWC, 2004, October 2005, Pages 79-115.

Pascal Hitzler: ( http://www.sciencedirect.com/science/article/B758F-4H16P4Y-1/2/d039e4784b224e95aafca856ecfb1edb )

Pascal Hitzler: Keywords - Ontology; Semantics; Entailment; Completeness; Computational complexity

Boris Motik: echo ian, observes that fragments exist which can be implemented with a set of complete rules

Bernardo Cuenca Grau: i'm worried about soundness and worried about what "sound and complete" means here. I don't understand the semantics

Bernardo Cuenca Grau: ...b/c you haven't implemented the OWL semantics, you've chosen some of the OWL DL vocabulary

Zhe Wu: we do care about completeness, but don't consider it critical

Zhe Wu: ... completeness is evaluated w.r.t. query answering for some benchmarks, etc.

Bijan Parsia: From a spec perspective, this fragment seems to be *implementation* defined...which is a bit worrisome

Bijan Parsia: My test for this would be, without looking at thier rules or using your rule engine per se, can i write an implementation from a publically available description?

James Hendler: I would point out that DB communities tend to do language/sublanguage without model theories very comfortably

Jeremy Carroll: what I hear from customers echos Zhe's comments.

Jeremy Carroll: ...I note that much of the questioning is hostile

Alan Ruttenberg: I agree

Jeremy Carroll: that may be b/c much of the questioning is coming from members with different user groups

Bijan Parsia: I would disagree with the assessment of tone...is it even relevant?

Carsten Lutz: I would strengthen Boris claim and say that most (if not all) other fragments admit forward chaining, which is sound and even complete,

Carsten Lutz: and the rules are easily derived.

James Hendler: I also find that Web 3.0 companies, including the folks interacting with us on the billion triple challenge, also come from the perspective Zhe represents

James Hendler: http://ebiquity.umbc.edu/blogger/2007/12/06/the-semantic-web-billion-triples-challenge-at-iswc-2008/

Ian Horrocks: it wasn't intended to be hostile. I was trying to understand whether Oracle would be interested in more well understood and explainable fragments

Ian Horrocks: ...e.g., dl-lite which can be implemented in a database system, and also in a rule system

Ian Horrocks: DL Lite, not PD* [Scribe assist by Sandro Hawke]

Carsten Lutz: Same applies to EL++

Discussion of PD* soundness and completeness in a rule based implementation, which scribe didn't capture

James Hendler: fwiw, those fragments got little or no traction with the folks I consult for - they care about parallelizability and performance over the more understood stuf - their work is largely heuristic anyway

Ian Horrocks: the problem with PD* is that it doesn't implement a subset of OWL, it implements PD*

Jeremy Carroll: it depends on what you mean by fragment of OWL

Alan Ruttenberg: I hear interest in co-ordinating on database fragments with Oracle

Bijan Parsia: to standardize a fragment, we need a well defined specification that we can all understand

Uli Sattler: Zhe, I might have sounded hostile, which wasn't intended: some of us simply have a specific reading for certain words like "reasoner", and I couldn't see how this could be possible.

Uli Sattler: Zhe, also, if you want to see how IntersectionOf can be simulated with someValues and AllValues, ask Carsten.

IRC aside on specifications, definitions, and implementations

The following IRC conversation happened in parallel to the in room verbal conversation and some other IRC exchanges. It continued until Ivan the point in the minutes where Ivan requests an end to side conversations (just before Semantic Subsets)

Bijan Parsia: we need an *implementation independant* spec

James Hendler: What I am arguing for is that there are some important communities out there to whom the fragments they care about are not those tied to Uli's definition of reasoner

Sandro Hawke: hendler, people are not really paying attention to IRC.

Uli Sattler: Jim, I appreciate this -- but "reasoner" was used on Zhe's slides, and i simply wanted to know in which sense.

James Hendler: Bijan - agree with needing a spec, but I'd point out most programming languages get by just fine with operational semantics - in fact, since you implement Pellet in JAva, in a certain sense you're trusting that they get it right in some sense -

Uli Sattler: Jim, I guess what we would like to see is a consensus of what we mean by "Tool/reasoner X supports feature Y"

Bijan Parsia: First, I'm not saying anything about the specification style....but at the moment we don't have a clear spec. I don't know where to start other than by looking at Oracle's implementation

James Hendler: Uli, how do we show "Java" supports "begin/end loops"? that seems to be something in the real world that we could model for some (not all) of our work

James Hendler: this is the point!! thw Owl language features all have operational semantics that are good enough for many people in many situations - so when Oracle says we support X, why do we need more than that

Bijan Parsia: Second, there are differences between programming languages and ontology/data modeling languages. I hear your point, but find the analogy rather unconvincing.

Uli Sattler: Jim, I would never dream of trying to do this - but i would like to try to say what it means for a reasoner to support feature X

James Hendler: What I'm arguing is that RDFS 3.0, or OWL Prime, might be better looked at less as ontology languages (leave that to OWL DL) then as useful data analysis languages

Bijan Parsia: But I don't see why "useful data analysis langauges" don't need a clear spec

James Hendler: this is what my nose is rubbed in when I attend the Sem Tech conference and places like that

James Hendler: bijan - the question is what is the definition of a clear spec.

Bijan Parsia: Furthermore, model theory is pretty easy way to specify something...at the moment, no one has proposed anythign else

Zhe Wu: if there is a set of rules defined as those in RDFS spec, is that clear?

Bijan Parsia: Zhe, perhaps

Bijan Parsia: note that they are informative

Bijan Parsia: But I would be interested in looking at such

Zhe Wu: they may be informative, however, that is how most people understand semantics

James Hendler: but there are no model theories for many things, and model theory is not the only way to spec other things - like these rule-based examples

Uli Sattler: Zhe, we would call this "operational semantics" or such like and would be split about how clear this is

Bijan Parsia: Understand != spec

Bijan Parsia: Again, my test is can I write an interoperable implementation without looking at your implementation

Uli Sattler: +1 Bijan's inequality

Bijan Parsia: At least my first test

James Hendler: i.e. Inverse(A,B) IFF s A p -> p B s

James Hendler: seems like a fine definition of inverse

Zhe Wu: if we agree on a set of rules, then interoperability is not an issue

Bijan Parsia: Not at all since I don't know what you -> means

Bijan Parsia: Zhe, no

Bijan Parsia: Not clear at all

Bijan Parsia: For example, i might no use those rules *in* my implementation

Zhe Wu: using Hendler's example rule,

Bijan Parsia: I might want to use a very different technique

Zhe Wu: if we agree on that, then we are interoperable

Bijan Parsia: Is that rule controposable?

Uli Sattler: The reading of rules, for example, differ in whether you have contraposition or not

Bijan Parsia: Was it meant as <->?

James Hendler: Bijan, that is either easily defined, or can be left to philosophers trying to write PhDs, in the real world, lots og languages work this way - but if you want something better - okay, we'll use SCL

Uli Sattler: and whether you "apply" it to all named individuals or to *all* individuals

Bijan Parsia: hendler, that's not true

Bijan Parsia: But c'mon, that wasn't even a partial spec

Bijan Parsia: And it was of one of the easiest bits

Bijan Parsia: Inverse

Uli Sattler: so, I agree that your defintion of inverse seems clear, but when you want to implement it, there are questions coming up

Bijan Parsia: Consider complementOf

James Hendler: ok, KIF

Bijan Parsia: English would do

James Hendler: I agree with Zhe

James Hendler: complementOf not in RDFS 3.0 for precisely that reason

Bijan Parsia: It was in OWL Prime

Uli Sattler: Again, I find englisch often clearer than things like "->' or such like

Evan Wallace: Or did you mean CLIF from the ISO standard, Common Logic

James Hendler: English ok w/me

Bijan Parsia: In any case, I'm asking for a spec. We can beat on the spec and if we find problems we find problems

Bijan Parsia: If we don't we don't

James Hendler: but anyway, the point I'm making is not to oppose model theory - but the problem is to get the model heory right we have to put restrictions on the languge that some of us cannot live with easily

Bijan Parsia: I don't know that that's true

Uli Sattler: Jim, I disagree:

James Hendler: this is why OWL LITE is a subset of DL - not of Full, so there is no fragments for Full - which is what i often get asked for

Uli Sattler: Jim, model theory doesn't restrict things?

Bijan Parsia: I'm very skeptical about it, but I don't know because I don't know what the current fragment actually *is*

James Hendler: Uli, so we could define the language fragment based on other concerns and then define it via model theory - that doesn't bother me at all - I'd be fine with that

Bijan Parsia: But I'm open to being convinced otherwise...but I'm more convincable by a proof of concept (at least) than high level discussion

James Hendler: so Oracle has implemented OWL prime - what did I miss?

Bijan Parsia: Implementation != specification

Bijan Parsia: And this is true for programming langauges as well

Uli Sattler: Jim, what would you define via model theory? The fragment or its semantics?

James Hendler: Uli - whichever you want - I'm not going to need to read that document anyway ;-)

Uli Sattler: Jim, I think we simply disagree what it means to *implement* a fragment

Bijan Parsia: There are langauges defined by *specs* (including Java, Common Lisp, C, C++) and those defined by *implementation* Perl, Python

Bijan Parsia: (at least historically)

Bijan Parsia: So, frankly, I don't want to port Oracles implementation. That's probably not even legal

James Hendler: fine - I want a fragment of OWL that is defined by *specs*

Bijan Parsia: I want a specification sufficient for independant implementation

Bijan Parsia: But jim, if the specs happen to do it by model theory and capture the language you want, what do you care?

Bijan Parsia: If the specs are clear enough for me I don't necessarily require model theory ( though it helps so we can understand the relation to existing OWL specs)

James Hendler: bijan - the poiunt is I don't care - and I said that - what I care is what is in the fragment first, how to define it second

Bijan Parsia: How do you know what's *in the fragment* without a definitio of what the fragmetn is?

Bijan Parsia: What's the difference?

Sandro Hawke: hendler, please stop talkin on IRC.

James Hendler: Bijan - you're arguing circularly - but I can cut through it - I have created a wiki page with a description of exactly which language features I want to include - how to define it in a spec is something I'm happy to discuss

Sandro Hawke: Jim, we're talkin in the room now, and need to focus on this discussion in the voice channel, so no more chatter on IRC, please.

Fragments: (Tractable) Fragments and other Fragment Proposals

Bernardo Cuenca Grau presenting from slides in person

Ian Horrocks: Bernardo's talk in email and at http://www.cs.man.ac.uk/~horrocks/F2F-Fragments.pdf

Bernardo Cuenca Grau: motivation of owl-lite was easier owl. b/c owl dl and full are rich and complex.

Bernardo Cuenca Grau: ...problem is owl-lite is broken b/c it doesn't address interactions between constructors

Bernardo Cuenca Grau: most features held out of owl-lite can be recovered through "back doors"

Bernardo Cuenca Grau: existing document includes fragments which

Bernardo Cuenca Grau: .... are well understood, documented, etc.

Bijan Parsia: A precursor to OWL Lite giving some of the rationale: http://www.aifb.uni-karlsruhe.de/~sst/is/WebOntologyLanguage/harmelen.htm

Bijan Parsia: Er...precursor discussion

Bernardo Cuenca Grau: we don't expect users to go over recent literature on tractable fragments, so wanted a single document

Bernardo Cuenca Grau: most of the languages I will describe are "families" of languages, we decided to keep 1 from each

Bernardo Cuenca Grau: 1st is EL family

Bernardo Cuenca Grau: ...used in bio-medical already

Bernardo Cuenca Grau: stress that these fragments are not academic exercises, there are direct applications to existing ontologies

Bernardo Cuenca Grau: 2nd is DL-Lite family

Bernardo Cuenca Grau: ... designed for large number of instances in database technology

Bernardo Cuenca Grau: approach is similar to what zhe described, do work in tbox, then pass to database system for query answering

Carsten Lutz: reiterate bernardo, but contrast with zhe's approach. dl-lite change the ontology to use database technology, not change the database technology

Pascal Hitzler: would be nice to get a literature reference to OWLPrima - the description on the slides was not clear enough

Pascal Hitzler: I could find nothing on the web defining OWLPrime

Boris Motik: Pascal, pD* has been described here: http://www.springerlink.com/content/366474250nl35412/

Alan Ruttenberg: another difference is in oracle you can query for classes, in dl-lite only instances

Bernardo Cuenca Grau: you can do tbox reasoning, but designed for abox answering.

Bernardo Cuenca Grau: I picked the particular dl-lite language b/c it is between rdfs schema and owl dl

Zhe Wu: is there a scalable implementation of dl-lite? commercial tool?

Zhe Wu: Uli, what kind of tool? what is the scalability?

Bijan Parsia: Zhe, to the first, yes

Bijan Parsia: To the second, no

Bijan Parsia: QuOnto

Bijan Parsia: (Not yet)

Uli Sattler: Zhe, yes ther is, I think: search for Quonto

Uli Sattler: Zhe, it is as scalable as it can get:

Uli Sattler: Zhe, because it translates queries into SQL queries and leaves everything in the DB.

Carsten Lutz: Zhe, I understand that you would like to do forward chaining. A lot of fragments can be captured in a sound

Carsten Lutz: (and even complete) way with this technique. I would like to learn what is your idea of tractability and

Carsten Lutz: scalability. Is it forward chaining per se, or is it a rule set that does not produce too many new facts?

Zhe Wu: Carsten, the scability and performan requires are determined by the market.

Zhe Wu: Carsten, people are asking for hundreds of millions of triples and beyond

Bernardo Cuenca Grau: next is Horn-SHIQ

Bernardo Cuenca Grau: ...can reason without disjunctions

Bernardo Cuenca Grau: ...and low complexity for query answering

Bernardo Cuenca Grau: other fragments dlp as a bridge to rules

Bernardo Cuenca Grau: ... but it may be more "hacky" that horn-shiq

Bernardo Cuenca Grau: questions for wg

Bernardo Cuenca Grau: ....1 do we fix owl lite

Bernardo Cuenca Grau: ....2 does that mean select one of these fragments

Bernardo Cuenca Grau: ....3 or do we present a menu of fragments?

Bernardo Cuenca Grau: not in slides - do we want semantic subsets of owl full?

Bernardo Cuenca Grau: ....e.g., owl full versions of these fragments? do we care about complexity of the full fragments? about compatibility?

Ivan Herman: request to drop side conversations

Ivan Herman: ... and focus

Semantic Subsets

Alan Ruttenberg: little time, can we start with semantic subset of owl full?

Ian Horrocks: semantic subset means no change to syntax, but sanction smaller set of conclusions

Jeremy Carroll: example is pd*, which specifies what semantic rules are thrown away

Peter Patel-Schneider: pd* throws away *parts* of rules

Ian Horrocks: this is picky

Sandro Hawke: hendler, are you able to call on the phone?

James Hendler: sandro, no.

Joanne Luciano: hendler, type what you want us to speak for you

James Hendler: what kind of fragment?

Sandro Hawke: Alan is chairing this session.

Joanne Luciano: hendler, do you have access to the slides?

Joanne Luciano: to Hendler: fragments of OWL 1.1, which: are the result of years of research, have “nice” computational properties, are already supported by tools

Joanne Luciano: to hendler: cover most existing ontologies

James Hendler: But there are fragments which are not included that have all those things as well - Oracle Prime being a perfect example

Alan Ruttenberg: Jim, please call in if you want to participate

Joanne Luciano: to hendler: Fragment Goals: suggest possible fixes to OWL Lite, inform the OWL community about recent research results, help users & tool designers

Alan Ruttenberg: how comfortable are people with this type of fragment

Alan Ruttenberg: ... does anyone want to say this is a lousy idea.

Peter Patel-Schneider: yes, its lousy b/c you can be arbitrarily picky

Ian Horrocks: its a lousy idea b/c it blows away the idea of interoperability

Bijan Parsia: qualm that methodological design principles are "unclear"

Bijan Parsia: ...guidance for making decisions seem more arbitrary, a dangerous rat-hole

Bijan Parsia: ... would rather people say they are incomplete than building incompleteness into fragments

Jeremy Carroll: in response to ian, any semantic subsetting would need to be clear that it is a subset of spec and an explicit, agreed semantic subset

Jeremy Carroll: ...e.g., oracle and hp would agree on semantic subset and interop on at-least the semantic subset

Sandro Hawke: +1 Jeremy -- "incompleteness" is fine When It's In A Specified Fragment, that is implementated in multiple places, etc.

Alan Ruttenberg: if we call this fragment or conformance level, it seems useful

Alan Ruttenberg: ...that baseline entailments are necessary, but additional entailments may be ok

Bijan Parsia: if we shift from language fragments to reasoner conformance I'm more comfortable

Sandro Hawke: Bijan, "Reasoner Conformance" might be a more useful notion here than "Language Fragments".

Sandro Hawke: ...I have examples of people specifying this at a tool level.

Jeremy Carroll: i'd be happy with such a rewording. i don't see it as notable

Alan Ruttenberg: does such a distinction help others

some affirmation to alan in room

Zhe Wu: ?

Alan Ruttenberg: he said it would be useful to say we support same entailments

Ian Horrocks: more comfortable defining conformance that fragments

Ian Horrocks: and jeremy's suggestion sounds like standardising implementations

Alan Ruttenberg: Jim, you still there. Hard to follow the IRC. I can read what you write if you want to respond.

Bernardo Cuenca Grau: users are comfortable with incomplete reasoning. swoop offering rdfs reasoner as a choice is an example of this

Bernardo Cuenca Grau: ...more comfortable with that than trying to specify semantic subsets

Pascal Hitzler: +1 to bernardo

Pascal Hitzler: bernardo also stressed the importance of a clear semantics as reference ...

Jeff Pan: i agree with bernardo and others.

Jeff Pan: ... implementation does not specify fragment.

Boris Motik: i just looked at pd* , this seems like definition. I think it is a useful fragment if evaluated a certain way.

Ian Horrocks: i didn't say pd* was bad, that we'd be standardizing an implementation. it was a reaction to jeremey's comments on what hp and oracle might do

Sandro Hawke: owl is unique to me b/c it doesn't specify what the tools do, people read into that. specifying the tools would be useful. as a customer I expect that and would like it

Joanne Luciano: what's "pd*"?

Sandro Hawke: PD* is referred to in Zhe's presentation.

Sandro Hawke: (from Herman ter Horst)

Zhe Wu: ina: it is not just hp and oracle, owlim, allegrograph as well

Bijan Parsia: justifying discomfort - seems likely that over time fragments specified in such a way are likely to move

Bernardo Cuenca Grau: on sandro's comment - we should specify reasoning services

Bernardo Cuenca Grau: ... it's not in the spec for OWL DL. for fragments the services descriptions would be useful

Sandro Hawke: i don't know what the terms are, the market decides

Sandro Hawke: It should be customer driven. When they want to find on the shelf, those should be the things defined in the spec. [Scribe assist by Sandro Hawke]

Ian Horrocks: its difficult to imagine semantic subsets not drifting apart

Ian Horrocks: ... it has been a success for owl that interoperability is so good, considering

Jeremy Carroll: responding to standardizing tools - yes. there is value to user if they know different tools perform the same

Jeremy Carroll: ... this wg could provide appropriate conformance levels where vendors and user community come together

Jeremy Carroll: ... clear that motivations from academic community are useful, but they aren't the only motivations

Sandro Hawke: +1 Jeremy: there is real value to the customers in knowing that a set of products will all do (at least) the same thing. It would be a service to the community for this WG to provide that.

Alan Ruttenberg: no one is saying market is unimportant

Uli Sattler: clarification on user needs?

Jeremy Carroll: users need some sort of specification, but don't need to know behavior is exact

Alan Ruttenberg: I want to poll for consensus on how to procede