F2F1 Minutes Session 7

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This is part of F2F1 Minutes.

OWL Working Group Meeting Minutes, 07 December 2007

DRAFT. Currently Under Review

See also: IRC log

Michael Smith

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


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

Joanne Luciano: +1

Sandro Hawke: i don't understand

Alan Ruttenberg: I want to know if people think these fragments are useful

Alan Ruttenberg: ... defined as a minimum set of entailments

Bijan Parsia: reasoners can conform to the language to different degrees

Ratnesh Sahay: subset of language + conformance level, is something similar to the way current languages (e.g) doing, like, Deprecated apis + core language( and specialized apis)
Michael Smith: subsets of entailments == conformance levels

Alan Ruttenberg: we should aim for something specified like pd*

Ian Horrocks: declarative...

Alan Ruttenberg: yes, declarative

Sandro Hawke: Q1 - The Working Group should (formally, precisely) define conformance levels, defining groups of reasoner which can do certain kinds of reasoning (all for a given OWL Fragment).
Sandro Hawke: Q1 - The Working Group should (formally, precisely) define conformance levels, defining groups of reasoners which can do certain kinds of reasoning (all for a given OWL Fragment).

Uli Sattler: we would later know e.g., what it would mean for a reasoner to conform to particular level?

Alan Ruttenberg: yes.

Jeff Pan: what does conformance level mean? is it in terms of benchmark?

Uli Sattler: provides example

Ian Horrocks: The Working Group should (formally, precisely) define conformance levels, defining minimum levels of inference that would be found?
Zhe Wu: q+

Carsten Lutz: degrees of incompleteness?

Ian Horrocks: The Working Group should (declaratively) define conformance levels, defining minimum levels of inference that would be found?

Alan Ruttenberg: degree of completeness

Alan Ruttenberg: ...fragments are syntactic fragments

Alan Ruttenberg: ...conformance levels are distinct

Sandro Hawke: Q1 - The Working Group should (declaratively) define (one or more) conformance levels, defining minimum levels of inference which would be performed (for a given OWL Fragment).
Achille Fokoue: yes if we are talking about a declarative way of defining minimum levels of inference

Jeff Pan: there might be difference between alan's and uli's suggestions

Alan Ruttenberg: distinction is unimportant now

Zhe Wu: when we, as a group define confromance levels, it is very useful to look at current market
Zhe Wu: including HP, Oracle, AllegroGraph, OWLIM etc.

Alan Ruttenberg: reads Q1 as above

Sandro Hawke: against - Jeff, Carsten, Ian
Achille Fokoue: +1 ( for a declarative approach)
Joanne Luciano: joanne raises hand
Sandro Hawke: abstain - none.
Sandro Hawke: BREAK.
Joanne Luciano: joanne lowers hand
Sandro Hawke: lots and lots of people raise their hands in favor.