[Top] [All Lists]

Re: [ontolog-forum] Logic, Datalog and SQL

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Christopher Menzel <cmenzel@xxxxxxxx>
Date: Mon, 12 Feb 2007 12:24:49 -0600
Message-id: <E00A3EC2-A0AD-4506-A5BF-48C4739D37AD@xxxxxxxx>
On Feb 12, 2007, at 11:53 AM, Pat Hayes wrote:
> [John wrote:]
>> ...
>> Following is a revised version:
>>     A formal ontology consists of a theory T stated in
>>     some version of logic and a nonempty vocabulary V
>>     of types and relations.  The names in V are divided
>>     in three disjoint subsets:
>>     1. Names defined elsewhere, which are used in one
>>        or more axioms of T.
>>     2. Names defined in T, which may be used in other
>>        theories.
> I would prefer that we don't say that names are "defined". Very few
> ontology languages provide for actual definitions of names, and
> several that once did (notably KIF) no longer do. Explicit
> definitions are semantically troublesome, practically of no actual
> use, create paradoxes, and generally have negative utility. The
> entire SWeb apparatus has no definitions in it anywhere, nor is it
> likely to in the future. It is very hard to even see what it would
> mean to define a globally useable name. Let us just say that names
> occur in ontologies, and ontologies constrain the meaning of names.    (01)

Strictly speaking, a definition in a theory T just *is* an axiom in a  
conservative extension of T (hence an axiom that constrains the  
meaning of the name so defined) that satisfies certain criteria.  I  
can imagine it being useful in some contexts to be able to say that a  
certain axiom counts as a definition, but the concept of definition  
is so often abused and ill-understood that it is probably best  
overall to avoid it, as you suggest.    (02)

-chris    (03)

Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/ 
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (04)

<Prev in Thread] Current Thread [Next in Thread>