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Re: Time for quintuples?

From: Bob Ferris <zazi@elbklang.net>
Date: Fri, 24 Sep 2010 01:12:45 +0200
Message-ID: <4C9BDEED.5010102@elbklang.net>
To: semantic-web@w3.org
Hi Nathan,

there is no problem, if only one cognitive characteristic statement 
exists in the graph. Then I can simply match the topic of the skill 
(from the example) with the topic of the cognitive characteristic 
statement, which should be associated with the "shortcut relation" (via 
cco:skill).
However, if I have for example three "shortcut relations" (e.g. a skill, 
an expertise and and interest) in a graph, which have all the same 
topic, I can't match them to the related cognitive characteristic 
statement (as you can also see in the original example[1]).
So I will need an elegant solution to address this issue. N-Quads are 
providing from my point of the basis for it, if I add semantics for 
relating the 4th element as reification statement of 
subject-predicate-object triple of the quad*. That means, I don't have 
to explicitly define the "reification triples" (via rdfs:subject, 
rdfs:predicate, rdfs:object). Furthermore, I should have the possibility 
to simply query (and reason) against this quad graph, e.g.

SELECT ?topic ?weight ?activity
WHERE { ex:AUser cco:skill ?topic ?cc .
	?cc cco:activity ?activity .
	?cc wo:weight ?weight .
	?weight wo:weight_value ?weight .
	 FILTER (?weight >= 0.6) }

The intended semantics might also be possible, if I separate each 
"shortcut relation" and its related detailed description in extra Named 
Graphs (as proposed in the two Named Graph propals, see links from the 
first mail). However, I'm unsure, whether I will get these semantics, 
when I will merge the Named Graphs, because as stated in "Named Graphs, 
Provenance and Trust"[2]:

"...how to resolve conflicts between different graphs, and how to 
determine A, are seen as pragmatic issues, to be dealt with by 
application developers, rather than logical issues to be dealt with by 
formal semantics..."

Furthermore, I read also several times (e.g. here[3]) that there are no 
consistent semantics re. merging named graphs or reasoning over them. In 
"Contextualized RDF Importing"[4] they are proposing some rules how this 
can be handled.

I hope, I clarified my concern a bit ;)

Cheers,


Bob


*one can also extend this idea re. a set of context/reification 
statements similar like Triplesets (however, this might cause further 
problems ;) )


[1] http://smiy.sourceforge.net/cco/examples/N3/cco_-_football_example.n3
[2] http://www2005.org/cdrom/docs/p613.pdf
[3] 
http://www.semanticoverflow.com/questions/757/which-owl-reasoners-understand-named-graphs
[4] http://www.w3.org/2009/12/rdf-ws/papers/ws33

Am 23.09.2010 23:26, schrieb Nathan:
> Bob,
>
> I'm having a little trouble understanding where the problem is, from
> your .ng example you have:
>
> ex:APerson
> cco:skill <http://dbpedia.org/resource/Football_(soccer)> ex:CC1 .
>
> ex:CC1
> a cco:CognitiveCharacteristic ;
> cco:topic <http://dbpedia.org/resource/Football_(soccer)>;
> wo:weight [
> a wo:Weight ;
> wo:weight_value 6.0 ;
> wo:scale ex:AScale
> ];
> cco:activity <http://sw.opencyc.org/concept/Mx4rwJRiEpwpEbGdrcN5Y29ycA> .
>
> I'm failing to see why this simply isn't:
>
> ex:APerson cco:skill ex:CC1 .
>
> ex:CC1 a cco:CognitiveCharacteristic ;
> cco:topic <http://dbpedia.org/resource/Football_(soccer)>;
> wo:weight [
> a wo:Weight ;
> wo:weight_value 6.0 ;
> wo:scale ex:AScale
> ];
> cco:activity <http://sw.opencyc.org/concept/Mx4rwJRiEpwpEbGdrcN5Y29ycA> .
>
> can you expand a little, concentrating on why the former will acheive
> what you want, whilst the latter will not?
>
> Best,
>
> Nathan
>
> Bob Ferris wrote:
>> Hello everybody,
>>
>> I thought recently (again) about the handling of detailed descriptions
>> of an triple and hence reification. I followed in the last time often
>> the approach of object-oriented context reification. That means, I
>> introduced a new concept to describe a relationship more in detail.
>> This approach works fine if there exist no property hierarchy.
>> However, I designed exactly an ontology[1] with this feature. The used
>> property there is cco:cognitive_characteristic[2], which has further
>> specific sub properties, and the applied reification concept is
>> cco:CognitiveCharacteristic[3].
>> Initially, this design should enable to define different cognitive
>> patterns of an agent, which have the same topic as object, e.g. one is
>> _interested_ in soccer, has some _skills_ in soccer and also some
>> _expertise_ in soccer. With the Cognitive Characteristics Ontology it
>> is possible to simple represent these statements as triples, e.g.
>>
>> ex:APerson
>> a foaf:Person ;
>> foaf:name "John Wayne" ;
>> cco:skill <http://dbpedia.org/resource/Football_(soccer)> ;
>> cco:expertise <http://dbpedia.org/resource/Football_(soccer)> ;
>> cco:interest <http://dbpedia.org/resource/Football_(soccer)> .
>>
>> However, these simple statements do not say anything about the levels
>> or weightings of these cognitive patterns of this person, rather then
>> something about the related activity, e.g. playing or watching, or
>> characteristic dynamics. Hence, one can use the
>> cco:CognitiveCharacteristic concept to represent this knowledge, e.g.
>>
>> cco:habit [
>> a cco:CognitiveCharacteristic ;
>> cco:topic <http://dbpedia.org/resource/Football_(soccer)> ;
>> wo:weight [
>> a wo:Weight ;
>> wo:weight_value 6.0 ;
>> wo:scale ex:AScale
>> ] ;
>> cco:activity <http://sw.opencyc.org/concept/Mx4rwJRiEpwpEbGdrcN5Y29ycA>
>> ] ;
>> cco:habit [
>> a cco:CognitiveCharacteristic ;
>> cco:topic <http://dbpedia.org/resource/Football_(soccer)> ;
>> wo:weight [
>> a wo:Weight ;
>> wo:weight_value 7.0 ;
>> wo:scale ex:AScale
>> ] ;
>> ] ;
>> cco:habit [
>> a cco:CognitiveCharacteristic ;
>> cco:topic <http://dbpedia.org/resource/Football_(soccer)> ;
>> wo:weight [
>> a wo:Weight ;
>> wo:weight_value 5.0 ;
>> wo:scale ex:AScale
>> ] ;
>> cco:activity <http://sw.opencyc.org/concept/Mx4rwO0J55wpEbGdrcN5Y29ycA> .
>> ] .
>>
>> ex:AScale a wo:Scale ;
>> wo:min_weight 0.0 ;
>> wo:max_weight 9.0 ;
>> wo:step_size 1.0 .
>>
>> Unfortunately, these detailed descriptions aren't related to the
>> intended cognitive pattern. In a simple use case on can match this
>> relation via the cco:topic property, which should have the same topic
>> as the cognitive pattern. However, this wouldn't work here.
>> Hence, we will need a mechanism, which binds the reification statement
>> to its triple. I tried here three different variants:
>>
>> 1. Named Graphs, where every triple and its related reification
>> statement is entailed in a separate graph (see [4])
>>
>> 2. Named Graphs, where every triple that should have a reification
>> statement is entailed in a separate graph, and the reification
>> statement is also the graph description, hence, type of both -
>> rdfg:Graph and cco:CognitiveCharacteristic (see [5])
>>
>> 3. N-Quads, where the reification statement is referred via the
>> context node (see [6])
>>
>> This result let me also think about the quintuple approach again. That
>> means, to be more concrete: a combination of the Named Graph and the
>> N-Quad approach, where the context node of the N-Quad represents the
>> reification statement of the relation represented by the related
>> triple and the surrounding Named Graph represents the "common"
>> provenance and trust information (as these use cases are often
>> proposed as common for Named Graphs). Would you agree with that
>> modelling?
>> For example:
>>
>> ex:NG1 { ex:APerson
>> cco:skill <http://dbpedia.org/resource/Football_(soccer)> ex:CC1 . }
>>
>> ex:CC1
>> a cco:CognitiveCharacteristic ;
>> ... .
>>
>> ex:NG1
>> a rdfg:Graph ;
>> dcterms:modified "2010-09-22T09:55:52+01:00"^^xsd:dateTime .
>>
>> This would also make the explicitly modelling of the reification
>> triples (via rdfs:subject, rdfs:predicate and rdfs:object) in the
>> reification statement, as proposed in the RDF Reification of the RDF
>> Semantics[7], obsolete.
>>
>> Cheers,
>>
>>
>> Bob
>>
>>
>> [1] http://purl.org/ontology/cco/cognitivecharacteristics.html
>> [2]
>> http://purl.org/ontology/cco/cognitivecharacteristics.html#cognitive_characteristic
>>
>> [3]
>> http://purl.org/ontology/cco/cognitivecharacteristics.html#CognitiveCharacteristic
>>
>> [4]
>> http://smiy.sourceforge.net/cco/examples/N3/cco_-_football_example.trig
>> [5]
>> http://smiy.sourceforge.net/cco/examples/N3/cco_-_football_example_02.trig
>>
>> [6] http://smiy.sourceforge.net/cco/examples/N3/cco_-_football_example.nq
>> [7] http://www.w3.org/TR/rdf-mt/#Reif
Received on Thursday, 23 September 2010 23:13:46 GMT

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