[Crm-sig] *** ISSUE *** Revision of scope note for E73 Information Object to specifically include named graphs

Richard Light richard at light.demon.co.uk
Tue Jul 29 00:06:10 EEST 2014


Martin,

Thank you for this: I now have a much better idea of what you are trying 
to express.  I can also now see how the AAT is relevant to the 
discussion: it is precisely a set of propositions with an identity, or 
(to use SKOS terminology) a Concept Scheme.   (However, I can't see the 
AAT being cited as justification for an assertion or set of assertions, 
so maybe it's not that pertinent an example.)

However, the AAT as a concept scheme is identified by the URI:

http://vocab.getty.edu/aat/

which yields a web page when invoked normally, and redirects to:

http://vocab.getty.edu/download/rdf?uri=http://vocab.getty.edu/aat/

when RDF is requested in the HTTP Accept header.  Every concept within 
AAT contains an assertion that it is skos:inScheme AAT.

So, in what way would you create a Named Graph (in your sense) for the 
AAT?  What URI would you associate with each triple in the concept 
scheme?  And what practical benefit does this give you, that simply 
using the URL quoted above doesn't give you?

Richard

On 28/07/2014 11:34, martin wrote:
> Dear Richard,
>
> On 28/7/2014 11:41 ??, Richard Light wrote:
>> Martin,
>>
>> I thought that a major merit of the CRM was that it was an abstract 
>> model, which could be instantiated using whatever technology was felt 
>> to be appropriate.  That being the case, I would be concerned if 
>> RDF-specific techniques were presented to the world as the only way 
>> in which a particular challenge ("implementing argumentation systems 
>> ...") could be tackled using the CRM.  Or are you talking 
>> specifically about RDF implementations of the CRM?
> I share your concerns :-) !
>>
>> Why can't "premises and conclusions" be modelled using reification, 
>> so they can then be given a unique URI? This is the sort of approach 
>> which the BM has successfully deployed, as I understand it.  I would 
>> be grateful if someone could provide a really simple concrete example 
>> which shows the need for the named graph approach.
> Your are right!
>
> Actually I see the "Named Graph" not as a particular RDF feature, but 
> at the level of abstraction that Simon pointed
> out: A set of propositions with a "historical" identity which is not 
> reduced to the identity of the set itself.
>
> The CRM uses an abstract data model of classes, superclasses, 
> properties, superproperties etc., which is more or
> less the stable core of all data structures and KR models used so far 
> in industrial systems. We have however adopted
> the term "property" from RDF, just to reduce the semantic gap for 
> people now. Originally, we used TELOS terms, but KIF, OIL was equally 
> compatible.
>
> The requirement to introduce argumentation structures into consistent 
> graphs of propositions is relatively new.
> Reification is an atomic mechanism, which does not allow for 
> describing that a set of propositions is believed
> together. Therefore it looses an important part of the semantics of 
> argumentation. A Named Graph is in my mind
> an abstarction which subsumes reification. Reification is a workaround 
> using a syntax which has not foreseen the problem before. Named Graph 
> is a NEW logical construct not found in any other industrial KR model, 
> and born out of a necessity that first showed up when integrating 
> different sources. (Before, one could say AI just slept in a one-truth 
> cyberworld with a god-like user or math on top of reality).
>
> I believe we need the Named Graph construct as a logical form, not as 
> an RDF syntax, if we want to integrate
> provenance of knowledge with the CRM. So far, we have evidence of two 
> real-life data structures, one is
> archaeological excavation records, and another description of medieval 
> book-bindings, which systematically
> register source of evidence and concluded facts. E.g., geometric 
> topology of stratigarphic units and microsopic
> stratigraphic interface properties are used to justify chronological 
> sequence. In a simple model, this is atomic,
> in a more general, it is probabilistic Bayesian. So, we would need a 
> "Typed Named Graph", which restricts the
> propositions in the Graph to a certain schema (topology, chronology), 
> and then a relationship "is evidence for"
> between the typed named graphs. The assertion itself forms part of the 
> belief implicit in the archaeological
> record.
>
> If there is any logician on this mailing list, a proper formulation of 
> such a construct and an abstract syntax for the CRM would be great to 
> have!!!
>
> We will try to suggest a graphic primitive, which is a bubble around 
> the propositions with a "hot spot" on the
> perimeter.
>
> Suggestions most welcome!
>>
>> To pick up on the suggestion of using the AAT as an example: in what 
>> way is the AAT a named graph?  Surely it's a SKOS Concept Scheme 
>> (plus)?  I think it would be impossible to give an example of a 
>> "well-known" named graph, for the reasons Simon has been explaining.
> Named Graphs are new, so none is really "well known", but I would 
> regard a skosified AAT as a Named Graph,
> as well as all the RDF junks for LoD, once RDF regards any RDF file as 
> a Named Graph. The only condition is, that
> two RDF Files with the same content and different URI are not regarded 
> as being identical (owl:same_as).
>
> Best,
>
> Martin

-- 
*Richard Light*
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