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Re: Classes and predicates as first class objects

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 15 Aug 2002 19:28:12 -0400
To: macgregor@ISI.EDU
Cc: www-rdf-logic@w3.org
Message-Id: <20020815192812A.pfps@research.bell-labs.com>

From: "Bob MacGregor" <macgregor@ISI.EDU>
Subject: Re: Classes and predicates as first class objects
Date: Thu, 15 Aug 2002 14:50:30 -0700

> This discussion started not as a question about the merits of DLs, but
> asked what you get when you sacrifice the ability to treat classes/predicates
> as arguments to other predicates.  Slightly paraphrasing:
> 
> > > > Clearly, not allowing this feature (classes and arc labels as
> > > > first class objects) buys description logics something.
> 
> Please correct me if I'm wrong, but my recollection is that CLASSIC allowed
> second-order syntax, and in fact made some claims as to the utility of doing
> so.  I my recollection is correct, then its not the case that we have to make this
> particular sacrifice to achieve the "benefits" of a DL.  Rather, the trade-off
> exists only for certain subclasses of DLs.
> 
> - Bob

I'm not aware of any second-order capabilities for CLASSIC.

Some versions of CLASS had an extra-logical connection between a class and
a related individual.  This allowed a back-door way of associating
properties with classes, much as in one of the stances on classes as
instances that I sent out to WebOnt a while ago.

peter
Received on Thursday, 15 August 2002 19:28:23 UTC

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