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Re: [URW3 public] Re: [URW3] ... three questions based on the last telecon

From: Ivan Herman <ivan@w3.org>
Date: Mon, 16 Jul 2007 13:32:57 +0200
Message-ID: <469B5769.8000401@w3.org>
To: Giorgos Stoilos <gstoil@image.ece.ntua.gr>
Cc: Peter.Vojtas@mff.cuni.cz, 'Ken Laskey' <klaskey@mitre.org>, public-xg-urw3@w3.org, mpool@convera.com

Giorgos Stoilos wrote:
> Hi Peter,
> Triples syntax is very specific to the RDF standard and *not* to every W3C
> standard. For example, triples syntax is not used in OWL (the standard
> describes a mapping to RDF graphs but a) it is very limited and cannot
> capture the OWL Semantics b) other syntaxes are preferred), 

??? why is the mapping limited?

Also: OWL is not equal to OWL-DL. OWL Full is fully described and
defined in terms of an extension of RDF semantics, and the there is a
very clear mapping between the OWL DL semantics and the corresponding
OWL Full semantics.

However: we indeed have to separate two things. There is a 'syntax',
essentially RDF/XML, which is nothing more than what it says: syntax.
And there is the triple model. Indeed, in some cases other _syntaxes_
are preferred. But that is a secondary issue in my view.

>                                                              while RIF will
> not care about triples syntax at all. 

This _may_ become correct if you refer to the RDF/XML syntax. It is not
correct if you refer to the model of RDF triples.

> I think you are mixing two issues here.
> 1) The specification of an uncertainty ontology, which describes the
> concepts and their relations, i.e. the schema, i.e. the TBox. So I don't see
> why we should add instances (ABox) in the ontology. At least in my
> understanding the Ontology is *not* meant to describe how to capture
> uncertainty in practice.
> 2) How to extend ontology languages, like OWL, to add uncertainty. Then we
> should take into account instances and thus the ABox and thus your example
> below has a purpose.
> So I don't understand how reification fits with the Uncertainty Ontology.
> Now, taken that triples are used in RDF (and not in OWL) I see your example
> below as an effort to extend RDF as to capture uncertainty, or about
> serializing an Uncertainty-OWL extension to RDF triples, which I don't see
> how is relevant.
> -gstoil
>> -----Original Message-----
>> From: public-xg-urw3-request@w3.org [mailto:public-xg-urw3-request@w3.org]
>> On Behalf Of Peter Vojtas
>> Sent: Monday, July 16, 2007 11:24 AM
>> To: Ken Laskey
>> Cc: public-xg-urw3@w3.org; mpool@convera.com
>> Subject: [URW3 public] Re: [URW3] ... three questions based on the last
>> telecon
>> Dear colleaguess (sent to public list and separately to KL and MP),
>> as I have pointed in the ontology page in Top Level comments by P.
>> Vojtas is there a mistake?, see
>> http://www.w3.org/2005/Incubator/urw3/wiki/is_there_a_mistake%3F
>> by W3C standards, basic information unit is a triple (subject,
>> predicate, object) which can be true or false in a structure (to avoid
>> discussion whether it is a sentence or proposition, w3c uses statement).
>> see e.g. http://www.w3.org/TR/rdf-primer/ for following example
>> http://www.example.org/index.html has a creation-date whose value is
>> August 16, 1999
>> here we can use reification for another writing asigning an identifier
>> to the statement
>> ex:triple1	rdf:type	rdf:Statement
>> ex:triple1	rdf:subject 	http://www.example.org/index.html
>> ex:triple1	rdf:predicate 	http://purl.org/dc/elements/1.1/creator
>> ex:triple1	rdf:object 	http://www.example.org/staffid/85740
>> ex:triple1	ex:creator	http://www.example.org/staffid/85741
>> especialy in our ontology discussion the triple
>> urw3:Sentence  	urw3:hasUncertainty  urw3:Uncertainty
>> should be by my opinion rewritten as
>> urw3:triple2	rdf:type	rdf:Statement
>> urw3:triple2	rdf:subject 	urw3:Sentence
>> urw3:triple2	rdf:predicate 	urw3:hasUncertainty
>> urw3:triple2	rdf:object 	urw3:Uncertainty
>> urw3:triple2	ex:creator	urw3:Mitch
>> and instance ( consider also an "instance"  ex:triple1
>> urw3:hasUncertainty  urw3:0.9)
>> as, e.g.
>> urw3:triple3	rdf:type	rdf:Statement
>> urw3:triple3	rdf:subject 	ex:triple1
>> urw3:triple3	rdf:predicate 	urw3:hasUncertainty
>> urw3:triple3	rdf:object 	urw3:0.9
>> urw3:triple3	ex:creator	urw3:Peter
>> urw3:triple3	urw3:tool	urw3:Bayes
>> The example with the german sentence (Mathias can help) is very usefull
>> (words morgen and Morgen are problematic) because it shows what can
>> happen. MP assigns an uncertainty to his own translation by expression
>> "if I've translated correctly". Nevertheless, by my opinion "Es regnet
>> morgen" is a problematic sentence because "Es regnet" is about present
>> and "morgen" with lower case m in the begining means tomorrow, it is an
>> adverb. So a problem accurs, what to do with a gramaticaly wrong
>> sentence (note that the word sentence I use here in the linguistical
>> sense, which in the W3c terminology can by defined appropriately by
>> corresponding triples, by defining predicates like subject, verb,
>> object, mode (manner), place and time). I would say either "Es regnet
>> heute morgen" or "Es wird morgen regnen".
>> Sorry for such a long mail, concluding I would like to say, please let
>> us use w3c terminology (arguing for necessity of an extensions of
>> standards we need be compatible with current standards). Next, the above
>> example shows we need to define our own prefix and rdf vocabulary for
>> uncertainty ontology.
>> Greetings Peter
>>>     *From:* Mike Pool
>>>     *Sent:* Friday, July 13, 2007 3:25 PM
>>>     *To:* public-xg-urw3-request@w3.org
>>>     *Subject:* three questions based on the last telecon.
>>>     Hi, all:
>>>     We've been having some great discussions during the meetings and I'd
>>>     like to pick up a few threads that came up in the last meeting.  I
>>>     reread these as I was trying to write up the minutes:
>>>     1)
>>>     Peter suggested that we use w3c standards as our guide for the
>>>     meaning of 'proposition'.  Peter, do you know if this is defined
>>>     somewhere by the w3C.  Could you point us to the definition?
>>>     2)
>>>     I argued that propositions, in the sense of the meaning of a
>>>     sentence that is invariant through all the paraphrases and
>>>     translations of the sentence, rather than assertions or sentences as
>>>     the kinds of things that hold probability values.
>>>     Kathy noted in the meeting that a problem with this definition is
>>>     that a system might assign different uncertainty values to 2
>>>     different logically equivalent sentences.   I can imagine that this
>>>     is possible, but where it occurs I would think it nothing more than
>>>     a weakness in the system, not in the definition I've suggested.  For
>>>     example, I might misunderstand 'Es regnet morgen' as 'it will rain
>>>     this morning' rather than 'it will rain tomorrow' (if I've
>>>     translated correctly) and assign it a different probability value
>>>     than that which I'm assigning to 'it will rain tomorrow'.  But I
>>>     think that anyone who observed my doing this would point out that
>>>     it's a contradiction, i.e., that since these things have the same
>>>     meaning, I'm obligated to assign them the same probability value.
>>>      In other words, it is in virtue of their representing the same
>>>     proposition that I'm obligated to assign them the same probability
>>>     value.    So, I think this only helps to underscore the fact that
>>>     when we explore our intuitions, we believe that propositions are the
>>>     real p.v. holders.
>>>     3)
>>>     Anne, you said at one point that "not all beliefs can appropriately
>>>     be represented as numerical values" and that it "glosses over
>>>     inconsistencies - beliefs may be logically incompatible".  I was
>>>     intrigued by the suggestion, can you say more?
>>>     Again, thanks all for a stimulating telecon on Wednesday.  Apologies
>>>     in advance if this address is not the right forum for these
>>>     discussions.
>>>     Best regards,
>>>     Mike Pool
>>>     --------------------------------
>>> ------------------------------------------------------------------------
>> -----
>>> Ken Laskey
>>> MITRE Corporation, M/S H305 phone: 703-983-7934
>>> 7151 Colshire Drive fax: 703-983-1379
>>> McLean VA 22102-7508


Ivan Herman, W3C Semantic Web Activity Lead
URL: http://www.w3.org/People/Ivan/
PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Monday, 16 July 2007 11:32:59 UTC

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