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RE: [ontac-dev] Type vs. Class -- Please vote

To: "ONTAC Taxonomy-Ontology Development Discussion" <ontac-dev@xxxxxxxxxxxxxx>
From: "West, Matthew R SIPC-DFD/321" <matthew.west@xxxxxxxxx>
Date: Sat, 21 Jan 2006 19:58:56 -0000
Message-id: <A94B3B171A49A4448F0CEEB458AA661F02CE51DB@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Dear Barry,    (01)

Time I came out of the woodwork on this - see below.    (02)


Regards    (03)

Matthew West
Reference Data Architecture and Standards Manager
Shell International Petroleum Company Limited
Shell Centre, London SE1 7NA, United Kingdom    (04)

Tel: +44 20 7934 4490 Mobile: +44 7796 336538
Email: matthew.west@xxxxxxxxx
http://www.shell.com
http://www.matthew-west.org.uk/    (05)


> -----Original Message-----
> From: ontac-dev-bounces@xxxxxxxxxxxxxx
> [mailto:ontac-dev-bounces@xxxxxxxxxxxxxx]On Behalf Of Smith, Barry
> Sent: 21 January 2006 09:03
> To: ONTAC Taxonomy-Ontology Development Discussion
> Subject: Re: [ontac-dev] Type vs. Class -- Please vote
> 
> 
> 
> This is the definition of 'class' provided in the W3C glossary
> 
> >class
> >
> > From RDF Semantics (2004-02-10) | Glossary for this source
> >(n.) A general concept, category or classification. Something used 
> >primarily to classify or categorize other things. Formally, in RDF, 
> >a resource of type rdfs:Class with an associated set of resources 
> >all of which have the class as a value of the rdf:type property. 
> >Classes are often called 'predicates' in the formal logical 
> literature.
> 
> 
> http://www.w3.org/2003/glossary/keyword/All/?keywords=class
> 
> It seems to me that this definition makes all the mistakes we should 
> be trying to avoid (incidentally the treatment of 'type' is 
> even worse).
> 
> 1. It confuses meaning ('concept') with referent ('class'/'type') 
> with expression or symbol ('predicate').
> 2. It confuses what is in the syntactic category of a predicate 
> ('predicate', 'property' ...) with what is in the syntactic category 
> of a noun ('class', 'type', ...)
> 3. It is circular ('a class is a resource of type rdfs:Class').    (06)

MW: So far I am mostly sympathetic.
> 
> The disadvantages of using a disjunctive compromise 'ClassOrType' 
> (Compare SUMO's ClassOrSet) are, I think:
> 
> 1. That we need both of those terms to refer to different things: 
> 'class' to the extension, 'type' to that which all the members of the 
> extension share in common.    (07)

MW: This is the bit I don't get. From where I sit a class/set/type/category
(the longer the concatenation the quicker people will want to pick one 
and the less they will care which) has a number of instances and a number
of axioms, and there is no need for two objects (e.g. class and type) any
more than a person needs to be two objects because it has arms and legs.    (08)

MW: I accept of course that there is the trivial restriction class of
"instances of X" which can be derived from the instance_of relation, but
that is entirely redundant as far as I can see.    (09)

MW: Please explain my error.    (010)

> 2. Ordinary people will use an ontology only to the degree that it 
> contains terms they are already more or less familiar with, and given 
> that we are providing definitions of our top-level terms there is no 
> reason to invent new coinages.    (011)


> 
> BS
> 
> At 07:52 AM 1/21/2006, you wrote:
> >Leo,
> >
> >I'd be satisfied with that solution:
> >
> >>Personally, I think a better methodology for these problematic
> >>terminology aspects is to choose the disjunction:
> >>Class OR Type
> >>And move on.
> >
> >Some formalisms, such as OWL, happen to use the word
> >"class", other use the word "type", and still others
> >may represent either one with a monadic predicate.
> >
> >We can just let the tools that support those notations
> >use whatever terminology is common in the community
> >that uses those tools.  The only thing that really
> >matters is the choice of a suitable underlying formalism,
> >such as Common Logic.
> >
> >For the recommended user notation, I would suggest a
> >version of controlled English.  For example, see the
> >summary of Attempto Controlled English (ACE):
> >
> >    http://www.jfsowa.com/logic/ace.htm
> >
> >As another very similar example, I wrote a grammar for
> >Common Logic Controlled English (CLCE):
> >
> >    http://www.jfsowa.com/clce/specs.htm
> >
> >There are many issues concerning human factors and suitable
> >tools for supporting such languages, but writing a grammar
> >for such a language is a development project, not a research
> >issue.
> >
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oordinatingWG
>    (012)



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