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Re: [ontolog-forum] Lightweight, middleweight, and heavyweight semantics

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Kingsley Idehen <kidehen@xxxxxxxxxxxxxx>
Date: Fri, 02 Jul 2010 19:41:01 -0400
Message-id: <4C2E790D.4050500@xxxxxxxxxxxxxx>
John F. Sowa wrote:
> After the SemTech conference and some further discussions on related
> topics, I realized that many of the debates about the kinds of logics
> and ontologies could be clarified with some useful distinctions.
> Different kinds of applications require different levels of detail
> and precision in the definitions and different levels of expressive
> power in the logic.
> To make the distinctions memorable, good labels are necessary.
> I suggest the following four levels of semantics:
>   0. Zero semantics:  Data with no explicit semantics of any kind.
>   1. Lightweight semantics:  Some semantic tagging with terminologies
>      or folksonomies, loose hierarchies such as WordNet, but no formal
>      definitions, logic, or reasoning methods.
>   2. Middleweight semantics:  Some formal notations, but only a modest
>      amount of logic and reasoning.
>   3. Heavyweight semantics:  Detailed ontologies represented in a
>      rich version of logic with extensive reasoning.
> There are gradations of levels from Comma Separated Values to Cyc,
> The Linked Data applications are at levels 0 and 1.  They usually
> depend on traditional terminologies and folksonomies that have
> no formal definitions.
> Most Semantic Web applications are at levels 1 and 2.     (01)

What constitutes a Semantic Web Application?    (02)

I would assume you are referring to Application Logic that sits atop and 
orchestrates RDF data sources, for instance?    (03)

If so, RDF is a form of Linked Data. Thus, Linked Data Spaces also hover 
between levels 0 and 2, I would think.    (04)

I certainly like your scheme, it will ultimately bring a lot of clarity 
to a pretty confusing subject area.
>  RDFS and
> RDFa use tags that don't have detailed definitions.  Light use
> of OWL supports middleweight semantics, but extensive use of
> all the OWL features begins to cross the boundary between
> middleweight and heavyweight semantics.
I am able to perform backward chained and/or contrained forward chained 
reasoning (using SPARQL CONSTRUCTs) against the massive live Linked Data 
Space we called the LOD Cloud Cache [1]. Examples include:
owl:sameas, owl:equivalentClass, owl:equivalentProperty, owl:inverseOf, 
owl:SymmetricProperty, owl:InverseFunctionalProperty, 
owl:TransitiveProperty, rdfs:subClass, rdfs:subProperty ..    (05)

[SNIP]    (06)

Links:    (07)

1. http://lod.openlinksw.com --- live LOD Cloud Cache instance with 17 
Billion+ triples
http://lod.openlinksw.com/fct/rdfdesc/usage.vsp?g=http%3A%2F%2Fdbpedia.org%2Fresource%2FJohn_F._Sowa&tp=3    (08)

-- some identifiers with you as co-referent
http://lod.openlinksw.com/describe/?url=http%3A%2F%2Fdbpedia.org%2Fresource%2FJohn_F._Sowa    (09)

-- DBpedia data
http://lod.openlinksw.com/describe/?url=http%3A%2F%2Fdbpedia.org%2Fresource%2FJohn_Sowa    (010)

-- Not so complete data from DBpedia
http://lod.openlinksw.com/describe/?url=http%3A%2F%2Fdbpedia.org%2Fresource%2FJohn_F._Sowa&sas=yes    (011)

-- merged data via "owl:sameAs" inference context and resulting union 
expansion (for better or worse) .    (012)

--     (013)

Regards,    (014)

Kingsley Idehen       
President & CEO 
OpenLink Software     
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen     (015)

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