02 Jul 2008

See also: IRC log






<bijan> Why not? You think I *like* to hear myself talk?

<Rinke> :)

<calvanese> so, bijna you have to say sth

<bijan> What an aribtrary restriction!

<Rinke> unfair

<bijan> Like forbidding class/property punning!

<bijan> sth?

<bijan> Is that Italian for STFU? :)

<calvanese> come on, usually you don't have problems in talking. the contrary would be harder :)

<bijan> Hence the need to mute myself!

<bijan> Oo, that' looks like I snubbed rinke

<Rinke> hm

<Rinke> ;)

<bijan> You can talk and I'll listen :)

<Rinke> sure, as if I feel like talking after you've been so rude

<Rinke> tss

scribeNick EvanWallace


<bijan> Yes!

<ivan> ???

<msmith> the scribee thinks they look good

<IanH> PROPOSED: accept previous minutes http://www.w3.org/2007/OWL/meeting/2008-06-25

<msmith> +1 to accept 2008-06-25 minutes

<Rinke> +1

<calvanese> +1

<MartinD> +1

<ivan> +1


<IanH> +1

RESOLUTION: accept previous minutes http://www.w3.org/2007/OWL/meeting/2008-06-25

<JeffP> +1

Action Items status

Act 163 completed

<bijan> Done and closed

<bijan> No

Action 156

<msmith> http://www.w3.org/2007/OWL/wiki/Annotation_System

<ivan> http://www.w3.org/2007/OWL/wiki/Annotation_System#Simple_Syntax_Example

Action 156 done

<trackbot> Sorry, couldn't find user - 42

<scribe> continued

action 157

<scribe> continued

action 158

<scribe> done and closed

action 159 continued

<trackbot> Sorry, couldn't find user - 159

<bijan> He is

action 161 continued

<trackbot> Sorry, couldn't find user - 161

action 161

<bmotik> OK, I'll just add it right away.

Diego will write up what his investigation revealed

<bijan> Subject lin contains ACTION-Number


<m_schnei> i step back from 159

jeffP: cmt on inconsistancy

<bcuencagrau> you need the data to have the inconsistency

action 165

Diego: Easy keys are compatible with key notion in DL-Lite

<bmotik> -q

Diego: we need to restict these keys in the same way
... the keys cannot be subtyped

diego to write up how easy-keys could be used in DL-lite

msmith: asked if we described unique names assumption in the profile document

<msmith> I see, I didn't realize this had changed

Boris: it is described

action 164

<scribe> done


<alanr_> could we get a review of what the issue was?

Issue 16

<bmotik> +q

<bijan> Peter's not here, and he's the issue raiser?

IanH: the issue was - could you annotate annotations?

boris: problem - you can annotate entities and axioms, but not annotations
... peter proposed that annotations could contain a set of other annotations
... having an axiom that contains another axiom is hard in RDF
... my proposal is to can the issue because both proposed solutions are quite hard

alanr: I wonder if the question might go away with rich annotations

<bmotik> +q

alanr: there are motivating use cases for this

<bijan> http://en.wikipedia.org/wiki/Data:_URI_scheme

<bijan> http://www.w3.org/2007/OWL/wiki/Reification_Alternatives

alanr: how is the reification in one of the proposed solutions harder than where we have done this elsewhere

<alanr_> Mcdermott was convincing to me....

<alanr_> one + level of indirection

bijan: may need to recommend how to construct annotations for meta-annotations
... set up your structure of annotations so that you always reify in a nice way
... we could work out the pattern for this

alan: the idea of structuring annotations works for new annotation but not for old rdf annotations

<bijan> data: uris could solve this

<bijan> But they are ugly

<bijan> Literals as well

ianH: are annotations inside annotations asserted in the KB?

boris: the problem is that there is no way in rdf to say this axiom contains an axiom
... as soon as its in a bag of triples in rdf it is asserted

<bijan> there's a queue!

boris: can't tell after whether the triple occured at the top level or inside another triple

alan: I'd be happy to work through the example with Boris over email

<alanr_> Note: I will have to leave at 2pm.

bijan: this problem of not having syntactic context is something I considered
... people who are tracking this should look at the reification table

skipping 67

issue 126

issue 126

alan: it seemed like there was clear consensus on an underlying Real datatype
... and floating point is promoted to this for reasoning

<bijan> +1 to disagree with type promotion

<bmotik> +q

alan: there was a question on whether or not non-numeric values of float like +inf were also promoted

<Zakim> msmith, you wanted to disagree on type promotion

msmith: I agree we want an underlying real datatype, but disagree promoting xsd: float

<alanr_> is it clear what "promotion" means? Perhaps Boris should explain.

<bijan> I also thing Reals shouldn't have NaN. Those aren't reals! Why make a clean datatype and then crude it up!

<alanr_> the argument is that floats are there to represent machine computations.

msmith: don't understand the point of having both xsd:float and xsd:decimal

<alanr_> This is an important use case for Science Commons

<alanr_> 1+

<alanr_> not 1+

<MartinD> +1

boris: promotion means to restrict float values
... I'm pretty happy with ditching float and double, but this will look bad

<bijan> "Ditching"? Isn't it that we "aren't adding"

boris: you might want to store these in an efficient way

<bijan> Floats aren't continuous

<Carsten> +1000

<bijan> I'm confused

<bijan> ?

boris: I would bet if we keep the continuous aspects of float, then now implementation will be correct

<bijan> It's arbitrary sized decimals

<MarkusK> yes, I also think that xsd:decimal supports no exponent notation

<bijan> It can't !

<bijan> There's too much here

<alanr_> http://www.w3.org/TR/xmlschema-2/#decimal

<bijan> Can we chunk the discussion a littl

boris: a possible way out is to define an owl:float and owl:real

<bijan> http://www.java2s.com/Code/Oracle/Data-Type/IS-NAN.htm

alan: wrt continuous aspect:

<MarkusK> (for the minutes) xsd:float also has non-numerical numbers, NaN and infinite

<MarkusK> s /numbers/values/

alan: effect on floats, the only consequence to considering them real would be
... asked some folk, they would prefer real

<m_schnei> (for the minutes, too) IEEE floats also have +/- 0, do xsd:float have too?

alan: also asked about +-inf and NaN
... they considered these to be essential
... the objective is to be able to transmit and contain numeric data in an OWL file

bijan: the first step I have is if we are going to talk about something with a binary rep.
... we can't avoid rounding, we can't separate the value space from the representation

<alanr_> OWL does not produce new floats in the course of reasoning.

ianH: it seems to me that we are proposing in owl to have a virtual float that is continuous

<alanr_> So precision issues are external to OWL - OWL would not disturb any precision or do any rounding.

bijan: so you are just treating the float rep as an idiosyncratic rep of reals

boris: the value space is the set of real numbers between the min and max of float

<alanr_> Ian asked my question

<alanr_> 2.0 float is not considered different than int float

carsten: I like this proposal
... either dropping float completely, or treating them as reals for reasoning

<alanr_> no float predicate, I think.

boris: floats are a subset of reals

carsten: treat float as a property of a real number?

boris: the reason for doing this is so that you can ship data around as reals

<Carsten> perfect

<alanr_> consider: oracle than answers between a and b, how many values. For float we decide to answer: Infinity , always

<bijan> One question at a time!

<bijan> Please!@

<bijan> I wanted to respond to the carsten questiona nd now we're off track

boris: if you have something like 1 / 0 then the ontology is unsatisfiable

bijan: there are 3 options for the predicate thing

<alanr_> comment: Lexical float doesn't work - because of defined rounding.

bijan: no predicate

alan: we want to capture the result of an experiment and that may include NaN values

<Zakim> alanr_, you wanted to mention nan as data bottom

alan: they don't care about how many discrete values between here and there

<bijan> the �value space�s of all �primitive� datatypes are disjoint (they do not share any values)

msmith: people using XSD already make the choice between xsd:float and xsd:decimal

<bijan> http://www.w3.org/TR/xmlschema-2/#rf-fund-facets

<bijan> (double and decimal are primitive datatypes in xsd)

msmith: given the fact that they chose xsd:float, we ought to respect the choice

<Zakim> msmith, you wanted to ask about the benefit of this proposal

boris: the reason that float is not put under decimal in xsd may be because of the 3 special values

<Zakim> bijan, you wanted to point to 4.2

<JeffP> the spec is somehow inconsistent

<msmith> http://www.w3.org/TR/xmlschema-2/#equal

bijan: the spec says the value spaces of float and decimal are disjoint

<alanr> Does it actually say they are disjoint, or does it not say they have a shared value space (negation or naf)

<msmith> it says disjoint

Issue 131

<Zhe> yes

<Zhe> let boris go first

boris: problem with OWL R profile is OWL R full version is not a syntactic fragment

the idea is to have basically 1 OWL R profile

boris: if the ontology is written in triples it is in OWL R if it is parseable as OWL R

Zhe: Yes. I do agree with Boris on this. It seems a bit odd to have these two versions.
... I see the value of combining the syntactic restriction into the profile

m_schei: regarding confusion - it is not confusing from an rdf point of view because

<bmotik> +q

m_schei: any sublanguage is a semantic sublanguage
... I don't share the argument.

boris: I think what is confusing is from an ontology point of view.

<bcuencagrau> +q

boris: you don't know what it means. You can't interpret it in an unambiguous way.

<Zakim> bijan, you wanted to talk about user perspective

<bijan> I'm still on the queue!

<bijan> No no!

boris: what is the point also from a user's perspective, when the meaning is ill-defined.

bijan: In my experience users find the semantic subsetting confusing.
... In our spec.s, all the other profiles are syntactic subsets

bernardo: I totally agree with Bijan on this. The purpose of OWL R is to define a language
... that is easily implementable using production rules.
... What people real care about is this ability to implement the reasoning using a rule engine.

<bijan> Yes

<JeffP> y

IanH: to M_schnei - what if they use some rdfs syntax and no rdfs interpretation is made
... wouldn't the user be surprised?

<Rinke> +q to ask about relation with DLP

m_schei: you would restrict the reasoning to rdf in a tool like Jena, you would be explicitly aware of this
... run the reasoning and see what inference graph is produced
... you of course have to know which reasoner you are using

Bijan: you will still be able to do the RDF style reasoning

<Zakim> Rinke, you wanted to ask about relation with DLP

Bijan: In OWLland people are used to having certain syntax indicate the reasoning features in the interpretation

<bijan> (DLP and hornSHIQ are also syntactic fragments)

rinke: when we started we had dlp, and horn-shiq and others
... How will this impact people who use DLP like stuff

<m_schnei> Motivation for OWL R was RDFS 3.0 / OWL-Prime

boris: Horn-SHIQ was dropped because there were too many fragments

<bijan> And a champion in the working group :)

boris: we just kept those that had larger user bases

<m_schnei> All the fragments in the beginning were *DL* fragments --> HENCE syntactic fragments

<bijan> All the fragments in the beginning were *OWL* fragments --> HENCE syntactic fragments

Boris: what remains is OWL R. You can still use production rules or other similar tools for it.

<bijan> OWL lite is a syntactic fragment of OWL DL which is a syntactic fragment of OWL Full

<m_schnei> Full fragements are always semantic fragments, they are always applyable on every RDF graph

Boris: We are just saying there is a syntactic check that can indicate which profile is being used.

<bijan> OWL DL and OWL Lite *are* fragments of full. What you say is false. And I'll stop the back chat ;)

Zhe: Oracle is planning to support this profile in the future and it is probable that we
... will include the capability to bypass the syntax check.

ivan: what I would like to understand is if we go with Boris' proposal and I'm in RDFland
... what exactly do I lose?

IanH: I guess you lose the ability to consider some graphs as OWL R.
... Like if you include SomeValuesFrom constructs.

Boris: you don't lose anything. The rules will work exactly as they are. You don't lose any
... expressive power. The syntax forbidden doesn't have rules for the corresponding reasoning.

bijan: in a way the fragment is saying these are the things we know how to do something interesting with.

<m_schnei> what is with the RDFS axiomatic triples?

<bcuencagrau> +q

Zhe: to Ivan's point, expressivity is not lost. Just some ontologies will be rejected, if syntactic checking is on.

bernardo: we have an additional benefit from specifying this as a syntactic fragment
... you can know if you are in the fragment, and that is a desirable feature.

<ivan> bye

<Rinke> bye

<JeffP> bye

<Zhe> thanks

<MarkusK> bye

<ratnesh> bye

<bijan> Yay to evan!

<m_schnei> bye

<Carsten> bye

Summary of Action Items

[End of minutes]

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