Kingsley, (01)
I want to emphasize that Guha is the chief architect of Schema.org.
He earned his PhD under John McCarthy at Stanford, and he wrote his
dissertation on contexts and microtheories. He implemented that
approach in Cyc, of which he was the associate director. (02)
Guha was also the chief designer of RDF, and he co-authored the
LBase (logic base) for RDF with Pat Hayes. So he knows that: (03)
KI
> GoodRelations assimilation does have the downside of its semantics
> being blurred. Fundamentally, Schema.org is a vocabulary with
> absolute minimal semantic fidelity. In short, GoodRelations assimilation
> is done by way of complete namespace replacement without any use
> of the following:
>
> 1. owl:equivalentClass
> 2. owl:equivalentProperty
> 3. rdfs:subClassOf
> 4. rdfs:subPropertyOf
> 5. owl:inverseOf. (04)
Guha is also a politician. So is Peter Norvig -- the research director
of Google, who co-authored a widely used book on AI. They know which
way the wind blows, and it's not in the direction of OWL. They also
know that English paragraphs are a better way to introduce ontology
and to lure in prospective users. (05)
KI
> In sense, GoodRelation's perceived assimilation into Schema.org is
> just another case of smart bridging that understands that there will
> be a time (very soon) when we get beyond all the *myopic* syntax and
> markup language distractions that currently obscure the value and
> power of entity relation semantics. (06)
I strongly agree. And I believe that Guha et al. have done their
homework in making sure the Schema.org hierarchy meets the logical
criteria above -- which, by the way, can be expressed more readably
in Aristotle's notation: http://www.jfsowa.com/talks/aristo.pdf (07)
To provide formal proofs of Aristotle's system, John Venn developed
a model theoretic foundation that can be and has been taught to
elementary-school children. If you can teach it to grade-school
kids, you have a chance of getting the idea across to the average IT
manager. See slides 31 to 35 of aristo.pdf. (08)
Recommended directions for the future: (09)
1. A base hierarchy such as Schema.org with English paragraphs
to describe each term *and* formal definitions upon request. (010)
2. Tools such as CEDAR (copy below), which runs circles around OWL
in performance on hierarchies of more than 900,000 terms *and*
has a far more flexible and powerful reasoning system. (011)
3. Notations that provide a bridge between ontology and mainstream IT.
UML diagrams would be an important part. Instead of OCL, I suggest
controlled NLs, such as Aristotle's and others -- supplemented with
more diagrams, such as John Venn's, Topic Maps, Concept Maps, etc. (012)
John
___________________________________________________________________ (013)
The following excerpt is from http://www.jfsowa.com/logic/sorts.pdf (014)
More recently, Amir and Aït-Kaci (2013) compared the CEDAR system
to six OWL-based reasoners: Fact++, HermiT, Pellet, TrOWL, RacerPro,
and SnoRocket. They compared them on four taxonomies that ranged in
size from 111,559 sorts or classes (Wikipedia) to 903,617 sorts (NCBI). (015)
For classification, CEDAR was among the three fastest for all four
taxonomies. On the Wikipedia taxonomy, it was five times faster than
the second best (Fact++). For querying, CEDAR beat all the others by
several orders of magnitude. The query time is the most important,
since a classified CEDAR taxonomy can be saved and reused. CEDAR
also detects cycles in the taxonomy, which are a serious source of
inconsistencies. (016)
Amir, Samir, & Hassan Aït-Kaci (2013) Fast taxonomic reasoning based
on lattice operations, CEDAR Technical Report No. 3, LIRIS-UFR
d’Informatique. http://cedar.liris.cnrs.fr/papers/ctr3.pdf (017)
For related issues, see the three slide presentations by Hassan A-K: (018)
Is it possible to make the Semantic Web a reality?
http://cedar.liris.cnrs.fr/papers/intis.pdf (019)
Reasoning and the Semantic web,
http://cedar.liris.cnrs.fr/papers/ontoforum.pdf (020)
Empirical study of high-performance triple stores,
http://cedar.liris.cnrs.fr/papers/Presentation_Cedar-PetaSky-LIP_ENS-Web-Site.pdf (021)
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