From: Thorsten Liebig <liebig@informatik.uni-ulm.de>

Date: Thu, 15 May 2003 10:11:48 +0200

Message-ID: <3EC34BC4.5060501@informatik.uni-ulm.de>

To: Matt Halstead <matt.halstead@auckland.ac.nz>

Cc: www-rdf-logic@w3.org

Date: Thu, 15 May 2003 10:11:48 +0200

Message-ID: <3EC34BC4.5060501@informatik.uni-ulm.de>

To: Matt Halstead <matt.halstead@auckland.ac.nz>

Cc: www-rdf-logic@w3.org

Matt Halstead schrieb: > > I am beginning to confuse myself with direct subClass relationships in > DAML+OIL. The example follows : If you transform your DAML+OIL code into Description Logics it will look like: > Class A > subClassOf > hasObject X 1* ( means property hasObject hasClass X > with cardinality 1 or more) (define-concept A (at-least 1 hasObject X)) > Class B > subClassOf A > > subClassOf > hasObject Y 1= > > subClassOf > hasObject Z 1* (define-primitive-concept B (and A (exactly 1 hasObject Y) (at-least 1 hasObject Z))) > Class X (define-primitive-concept X) > Class Y > subClassOf X (define-primitive-concept Y X) > Class Z > subClassOf X (define-primitive-concept Z X) > What I am trying to do > > Class A has a property hasObject that can be one or more objects of > class X. Now I want to make a more specialized form of Class A called > Class B that is a subclass of A, but has the restrictions that it needs > exactly one object of Class Y and at least 1 or more objects of Class Z. > Class Y and Z are more specialized forms of Class X. If I take away > the subClass of A restriction of Class B then I can still look at it and > say members of Class B are certainly members of Class A. No, since A is defined with a necessary, but not sufficient condition an object is of class A iff it is explicitly defined as an object of A. > But now I seem > to have lost the explicit feeling that subClass of A gave, especially > when using an editor such as OilEd. I'm not sure about your question here, but if you remove the subClassOf statement and define A with help of a necessary and sufficient condition you can deduct that B is a subClassOf A. (For example the Racer DL-reasoner will do that if you feed him with the above by removing "A" from the definition of B and changing "define-primitive- concept" with "define-concept" in the definition of A). > The interpretation of multiple contraints on the same property > > I need to understand if my thinking is correct. The way I interpret > Class B is as follows : > > There are 3 anonymous classes that Class B is some function of. > > 1) the class of all individuals that have at least 1 or more hasObject > properties of type X > > 2) the class of all individuals that have at exactly 1 property > hasObject of type Y > > 3) the class of all individuals that have at least 1 or more hasObject > properties of type Z > > 2) and 3) are subsets of 1) > > We now form the conjunction of these restrictions, so that Class B is > the class of individuals that have exactly one hasObject property of > type Y and at least one or more hasObject properties of type Z, and that > this forms a subset of the class of individuals that have 1 or more > hasObject properties of type X. The fact I have used subclass say that > these are necessary, but not sufficient conditions for membership. > > > Is my interpretation is correct? > > regards > Matt ThorstenReceived on Thursday, 15 May 2003 04:18:41 GMT

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