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RE: DAML-S expressiveness challenge #1

From: Tim Finin <finin@cs.umbc.edu>
Date: Sat, 16 Jun 2001 13:29:30 -0400
To: "David Martin" <martin@AI.SRI.COM>, <www-rdf-logic@w3.org>
> From: www-rdf-logic-request@w3.org on Behalf Of David Martin
> Sent: Thursday, June 14, 2001 5:29 PM
> ...
> (1) Can the DESIRED CONSTRAINT be expressed in DAML+OIL, and if not,
> is it likely that DAML+OIL will evolve to allow its expression?

I recall that versions of KL-ONE had various kinds of
constraints that could span roles and role chains.  The equality
constraint was the one in the example used to explain the general
feature.  I think I've seen this in lots of KR languages in the DL
family.  A quick search on the web to refresh my memory revealed a 
paper by Alex Borgida I had not previously seen:

  Extensible Knowledge Representation: the Case of Description Reasoners
  JAIR 10 (1999) 299-434.

which discusses the utility of adding an equality constraint which
holds between two role chains as well as the difficulties in adding
this to a KR language.  In fact, he motivates this by the problem of
describing actions and subactions:

  Let us consider the extensions needed for a rather complex new concept
  constructor: same-as. The semantics of same-as([f1...fn],[g1...gm]),
  as introduced earlier, is that it denotes individuals for which
  the two attribute chains [f1...fn] and [g1...gm] have the same
  known filler. (The attributes must each have exactly one filler.)
  This constructor is very useful in representing the relationship
  between actions and subactions. 

Of course, I'm not sure what the consequences would be of
adding this to DAML+OIL.  I'm sure it would make some operations
(e.g., subsumption) *much* more difficult. But, it *is* an extremely
useful feature from a modelers point of view.
Received on Saturday, 16 June 2001 13:23:29 UTC

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