Re: [foaf-dev] Previous relations and predicate weightings

Hi Robert,

On 3/31/2011 1:10 PM, Rob Stewart wrote:
> Hi Bob,
>
> Many thanks for your reply. In short, the reason for the rely in
> responding was that I attended, yesterday, "Understanding Provenance
> and Linked Open Data" [1] in Edinburgh.
>
> I pointed out the Cognitive Characteristics Ontology to the group,

Thanks a lot for doing so!

> which included to team working on the Open Provenance Model [2], which
> I think encapsulates 10 existing Ontologies that provide partial
> provenance, which includes Dublin Core. Edoara Pignotti, at Aberdeen,
> immediately saw a purpose for CCO in one of his project, PolicyGrid
> [3].

Oh, that's interesting. Please let me know, if you'll need further 
guidance and information re. CCO and related ontologies.

> The questions surrounding the seminar involved a discussion about
> where provenance should sit in the Semantic Web. Should it be
> standardized within the RDF framework?

Yes, the basis should be provided by the RDF framework, i.e., (from my 
point of view) statement identifiers (see, e.g., [1]) and graph 
identifiers (which are already hot debated in the RDF WG).

> Is this what referencing
> NamedGraphs was for? Should it be up to the Ontologies (such as OPM)
> to define annotations for provenance?

Yes, the knowledge representations have to be powered by ontologies. 
AFAIK, OPM is a leading component re. the work of the Provenance XG [2], or?
Albeit, from my point of view, provenance modellings and the domain of 
CCO, cognitive patterns, are orthogonal to each other, i.e., I can 
assign to each description that is modelled with the help of CCO further 
provenance expression, e.g., a creator of statements. I use CCO to 
especially model internal context. Provenance information is, from my 
point of view, generally external context.

> Here's a question relating to CCO. In the example the web [4],
> regarding the BBC radio sevices, weighted cco:interest is used. Could
> this be applied to to any cco predicate?

Do you mean a simple and a more detailed description? - If this is the 
case, yes. However, this is not a modelling feature of CCO. It is rather 
a knowledge representation design pattern that is applied in CCO. It is 
called property reification and its related definition can be modelled 
with the help of the Property Reification Vocabulary (PRV) [3].

> I realize that cco:interest
> is mapped to foaf:topic_interest,

Yes, this step was necessary to position the interest relation in a 
hierarchy of cognitive pattern (cognitive characteristics). 
Consequentely, a domain shift from interests modelling to cognitive 
characterstics modelling was necessary. Albeit, this mapping is simply 
an equivalence property axiom.

> but was wondering if similar maps
> existed which would allow one to specify a weighting for the
> foaf:knows (or equivalent) property, which I think is such a vague
> term (even in the foaf defintion of "knows"), that such weightings are
> entirely necessary.

Generally, this implies a reification, since currently it is only 
possible to express binary relations with the help of RDF Model 
directly. For this reason, you have to create (or reutilize if 
appropriated) a (reification) class to have a basis to model a n-ary 
relations. Toby Inkster illustrated on SemanticOverflow such an example 
[4] for this concrete case, which I would like to quote here:

# let's start with a simple statement (re. PRV a shortcut relation); 
thereby, :friend can be seen as an equivalence property to foaf:knows

<#alice> :friend <#bob> .

# this an instance of the (reification) class :HumanRelationship

<#ab>
     a :HumanRelationship ;
     :participant <#alice>, <#bob> ;
     :relationshipType :friendship ;
     :since "2008-04"^^xsd:gYearMonth .

In this example he added a property to model the relationship type (here 
:friendship) and time instant that express the beginning of this 
relationship. Besides, you can also add a weighting (e.g. by utilizing 
the property wo:weight[5]).
Moreover, you can now define a property reification definition to 
express that these two information resources belonging semantically 
together.

ex:HumanRelationshipReification a prv:PropertyReification ;
    prv:shortcut :friend ;
    prv:shortcut_property :releationship ; # this could be 
:releationshipType, too
    prv:reification_class :HumanReleationship ;
    prv:subject_property :participant ;
    prv:object_property :participant .

So the example (the reification class of it) from above would then look 
like

<#ab>
     a :HumanRelationship ;
     :participant <#alice>, <#bob> ;
     :relationshipType :friendship ;
     :since "2008-04"^^xsd:gYearMonth ;
     :relationship :friend .

> I realize that cco is somewhat influenced by the
> Weighted Interest Ontology,

Yeah, the original Weighted Interest Vocabulary [6] is one interest 
ontology amongst others that I unioned in the Weighted Interests 
Vocabulary [7]. The latter one is the predecessor of CCO and was 
necessary since CCO serves a broader domain (cognitive patterns instead 
of interests modelling).

> but would like to know if the Domain and
> Range of this predicate  could be transfomed to be something far more
> general like foaf:Agent or owl:Thing?

Which predicate? From my point of view the domain that is covered by CCO 
is quite appropriated. Please note that the Weighting Ontology is a 
simple specialized ontology that is designed to express a quite general 
issue (in this case weightings). Hence, this ontology is orthogonal to 
CCO. On the other side, PRV is designed to enable a mechanism (property 
reification) that is re. a knowledge representation hierarchy one level 
below, i.e., on the vocabulary level.

Please don't hesitate to ask further questions re. the application of 
CCO, WO and PRV.

Cheers,


Bob


[1] http://lists.w3.org/Archives/Public/public-rdf-comment/2011Jan/0001.html
[2] http://www.w3.org/2011/01/prov-wg-charter.html
[3] http://purl.org/ontology/prv/core#
[4] 
http://www.semanticoverflow.com/questions/2398/which-type-of-reification-do-you-use/2405#2405
[5] http://smiy.sourceforge.net/wo/spec/weightingontology.html#weight
[6] http://xmlns.notu.be/wi/
[7] http://purl.org/ontology/wi/core#