Re: clarifying clarifying ontologies

Peter Clark <>
From: Peter Clark <>
Message-id: <>
Subject: Re: clarifying clarifying ontologies
To: (Eduard Hovy),
Date: Tue, 8 Aug 1995 11:12:13 -0500 (CDT)
In-reply-to: <v02120d77ac4c185c0bfe@[]> from "Eduard Hovy" at Aug 7, 95 07:33:50 pm
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>> Taxonomies of "concepts" (or even "predicates") without axioms (or their 
>> moral equivalent) that pin down their intended meaning are not at all 
>> useful. [Ken Forbus]

> This very strong statement might be true for qualitative physics, but it 
> certainly isn't for NLP.  Most large NLP systems, parsers and generators, 
> find it convenient to use taxonomies. The systems tend to need to know 
> what general class of thing (syntactic or semantic, depending on the system)
> a symbol belongs to, in order that it may be properly handled.  That's what 
> a taxonomy provides. [Ed Hovy]

Ed - 
   I'm not sure if you're giving enough credit to your NLP systems. The
fact is, they *do* have axioms pinning down the intended meaning of the 
taxonomic symbols -- only those "axioms" are buried in the NL software which 
uses the taxonomies, rather than explicitly listed (which is fine given their
task). Consider: How do you know if you've put a symbol (ie. linguistic term
such as "engine") in the wrong place in the taxonomy? Answer = the NL 
software generates garbled/silly sentences. In other words, the 
software has assigned the wrong (linguistic) meaning to the symbol. 
The NL software defines *what it means*, in linguistic terms, to be a 
two-place-relational-process (say) eg. that they have a domain and range,
that they can be realized linguistically as <domain><relation><range>, etc.
The symbols in the taxonomy are certainly not of the vacuous nature 
which I think Ken Forbus was hinting at. I don't see any conflict 
between NL work and Ken's position: NL systems use more knowledge than 
just an isa-hierarchy too!

		Best wishes,


Peter Clark (   Department of Computer Science
tel: (512) 471-9565                  University of Texas at Austin
fax: (512) 471-8885                  Austin, Texas, 78712, USA.
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