Individual vs Individual-ThingMike Uschold <firstname.lastname@example.org>
From: Mike Uschold <email@example.com>
Date: Fri, 28 Jul 95 17:43:21 BST
Subject: Individual vs Individual-Thing
Cc: Piet-Hein.Speel@2488TAUX.urlnl.sprint.com, firstname.lastname@example.org,
It appears that for the practical purpose of building an ontology, the
class Individual is utterly useless. It exists purely for theoretical
reasons of avoiding nasty paradoxes.
* the only difference between an Individual and an Individual-Thing is that
only the former may contain Unbounded entities.
* the extension of Unbounded is empty
Therefore, one should never create an instance of Individual, but rather
of Individual-Thing. Yet, I see in various ontologies that people DO
define instances of Individual. However, it seems that:
* this causes no harm;
* those instances could be instead of Individual-Thing and this would be
equally correct logically (and possibly identical in meaning?);
* the only benefit of using Individual-Thing instead of Individual is
one of conceptual tidiness; i.e. it hardly matters.
1. Is this analysis correct?
2. Is there any other reason why one should prefer to
create instances of either Individual or Individual-Thing?
Mike Uschold, AI Applications Institute,
INTERNET: M.Uschold@ed.ac.uk The University of Edinburgh,
Tel: (031) 650 2732 80 South Bridge, Edinburgh EH1 1HN
Fax: 650-6513 Scotland