Re: DAML and reification

From: Jim Hendler (
Date: 03/05/01

At 12:42 PM -0500 3/5/01, Peter F. Patel-Schneider wrote:
>The problem is just what is supposed to be the meaning of reification in
>RDF.  There is no guidance from the RDF spec in answering this question.
>(Consider the DAML axiomatization---it provides no meaning for
>reification beyond the totally uninterpreted data structures.)
>Should we be answering this question in advance of RDF answering it?  I
>don't think so.  DAML+OIL is an ontology language, not a language for
>representing and reasoning about statements.

While I know what you mean, there are some people (probably including 
me) who would see these clauses as contradictory.

>One way of geting what you want would be to be able to tag real statements
>somehow.  This is NOT reification, but I don't think that tagging needs
>reification at all.  Using reification for tagging is like using the entire
>waste heat output of a malfunctioning nuclear power plant to heat your
>Peter Patel-Schneider

I think "tagging" in some form is a crucial thing for the language to 
have - as we move to rules, I think it wil be crucial (I will want to 
know where rules come from, and maybe use that to break the 
inevitable A->B, B->C, C->A loops that might arise from distributed 
rule definitions).  The semantics of SHOE (not as formal as DAML) 
focused a lot of effort on claims, and we make use of them in a 
number of ways.  I also agree w/Peter that we may not want to buy 
into the full RDF reification within the "logical interpretation" 
aspects of DAML+OIL+?x

Dr. James Hendler
Chief Scientist, DARPA/ISO	703-696-2238 (phone)
3701 N. Fairfax Dr.		703-696-2201 (Fax)
Arlington, VA 22203

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