Dear Pat, (01)
Ian's surprise at something being both an individual and a class is probably
my fault, because in ISO 15926 we used this term for something that exists
in space-time, i.e. a spatio-temporal extent. You would probably be less
concerned to know that Ian is surprised when it seems that a spatio-temporal
extent can also be a class. Of course this is not what OWL means by an
individual. ISO 15926 is of course quite happy about classes or individuals
being members of classes (as indeed is the IDEAS ontology that Ian
mentions). (02)
Regards (03)
Matthew West
Information Junction
Tel: +44 560 302 3685
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matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
http://www.matthew-west.org.uk/ (04)
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> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Pat Hayes
> Sent: 20 January 2009 17:55
> To: [ontolog-forum]
> Subject: Re: [ontolog-forum] Next steps in using ontologies as
> standards
>
>
> On Jan 20, 2009, at 8:51 AM, John F. Sowa wrote:
>
> >
> >> [ Ian Bailey wrote:] .... I'm
> >> not sure OWL and RDFS give you a proper foundation for ontology
> >> development - there are some very strange things in the W3C spec
> >> about how an individual in one ontology can be a class in another
> >> (bizarre even in an intensional approach).
> >
> > I very strongly agree. RDFS and OWL are horrible examples of how
> > *not* to design an ontology language. The designers started with
> > two disastrous implementation-based assumptions:
> >
> > 1. They wanted to reuse their XML-based parsing tools by forcing
> > everything into the world's worst syntax.
> >
> > 2. They forced a weird semantics in which the only relations
> > are dyadic. That means that you can't even say 2+2=4
> > because the "+" operator is triadic: it takes two inputs
> > and generates one output.
> >
> > These two blunders are the source of those bizarre features you
> > mention above. You can't entirely ignore RDF and OWL because
> > they were foisted on a large set of people who didn't know enough
> > to see that they were dupes in a Ponzi scheme. But you should
> > always preserve your sanity by thinking in terms of something
> > better, and Chris P's book is a good place to start.
>
>
> ---------
>
> On Jan 20, 2009, at 9:17 AM, paola.dimaio@xxxxxxxxx wrote:
>
> > when I first came to this forum I made it clear that
> > (for me at least) 'semantic' and ' ontology' are not equal to RDF/
> > OWL, despite a lot of misleading indoctrination perpetrated by
> > semantic web institutions
> >
> > ( I recently began arguing with a tutor at ASWC summer school who
> said
> > that an owl file is is an ontology in the w3c sense, and I wanted to
> > cry)
> >
>
> ------
>
> Hey, guys, lighten up. (A Ponzi scheme?? Indoctrination? Foisted?
> Dupes? Wanting to cry because OWL is an ontology language?). Nobody,
> even the people who wrote their specs, claim that RDF and OWL are the
> ultimate solution or to all problems. But (1) they do represent a
> viable approach to the problem they were designed for, which was to be
> machine2machine communication notations for the semantic web, and (2)
> if we must criticize them, at least let the criticism be informed.
> Almost everything that John says here is just wrong.
>
> Ian's complaint was the 'bizarre' property of RDF (not OWL-DL, in
> fact, though this will change in OWL2) which allows a class to be an
> individual. John says "I strongly agree", which is strange, as this
> particular property is foundational also to Common Logic, a project
> with which John is very publicly associated.
>
> First, to Ian: In fact, its even more bizarre than you think: one
> thing can be both an individual and a class (and a property) in the
> very same ontology. But this only seems bizarre if you have been
> indoctrinated by an old-fashioned and limited perspective on
> representational formalisms. This particular indoctrination is
> widespread, and it was no more than common sense until about 15 years
> ago, when some basic advances in logic showed that the traditional
> 'layering' of descriptions into individuals/classes/properties/
> metaclasses/etc. was (a) not necessary and (b) expressively very
> restrictive. One can keep the categories but abandon the strict
> layering - in effect, allowing a given thing to be in many 'layers' at
> once - and no disasters arise, if one cleaves to a certain simple,
> natural syntactic discipline (which is built into both Common Logic
> and RDF). The result is greatly increased expressivity and a formalism
> which 'naive' users invariably find quite natural, and which makes
> perfect semantic sense. For example, in RDFS the class of all classes,
> rdfs:Class, contains itself. This "ought" to be impossible, a
> conceptual error. Naive users tend to find it simply obvious; it turns
> out, they are correct. The perception of bizarreness that you report
> is felt only by those who have received a training in one of the
> classical indoctrinations, typically an undergraduate course in
> mathematical logic. No-one has yet written a basic logic text which
> uses the newer insights, unfortunately. There is a lesson from the
> history of OWL. OWL-DL, the most widely used version, rejected this
> generalization and kept the traditional layered structure. The
> pressure from users, including consortia of professional ontology-
> writers, to relax this restriction was overwhelming, and the first
> revision of OWL, OWL2, under final review as we write, will move to a
> version of the newer approach.
>
> To John: several points. (1) RDF syntax is in fact (that is,
> definitively according to the specs) defined abstractly, as a graph.
> An RDF graph is Pierce's graphical logic notation without negation.
> The XML serialization is only one possible serial syntax for RDF, and
> others are also in wide use. I personally refused to use the XML
> syntax in the RDF semantics document, as its relationship to the graph
> syntax, relative to which the semantics of RDF are defined, is so
> obscure. (2) Its true that RDF and OWL syntax is restricted to the
> (binary + unary) (= property + class) case; but this is hardly
> "weird". The fact that this is expressive enough for arbitrary logic
> has been well-known for almost a century, and is relied upon by a wide
> range of Krep notations and database conventions. It underlies the
> famous 'case-role' approach to giving more 'natural' expression of
> complex predications, as I am sure you know. So in this regard, RDF is
> simply following the herd. The binary reduction has both pros and
> cons. The cons are obvious and often noted, but the most important pro
> is that it permits the graph syntax to eliminate all notions of cyclic
> ordering on arcs, so that graphical syntax reduces simply to a
> collection of directed arcs. This was the primary reason for its use
> in RDF, in fact. (3) Neither XML nor the use of the unary/binary case
> have anything at all to do with the "bizarre"ness that Ian mentions.
>
> To Paula: An OWL file *is* an ontology in the W3C sense. All this
> means is that (1) "an ontology" refers to a collection of formal
> sentences, which has been accepted terminology in this field since its
> inception, and (2) "in the W3C sense" means that the formalism being
> used is one of those sanctioned by a W3C-published specification
> document, so that existing Web processes which conform to the
> standards can emit, transmit, input, parse and process it
> appropriately. If this makes you want to weep, you are working in the
> wrong field. Notice that nothing here says or even hints that there
> cannot also be other formalisms or ontologies.
>
> Pat Hayes
>
>
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