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[ontolog-forum] OWL Subclass Existential Reasoning

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Mark A. Hatcher" <markallanhatcher@xxxxxxxxxxx>
Date: Sun, 18 Oct 2009 23:04:02 +1100
Message-id: <4ADB0432.4020401@xxxxxxxxxxx>
Dear all,    (01)

I have struggled for too long by myself to try and understand the 
following.  If anyone can help, it would be much appreciated.    (02)

I create a class in OWL and then define a subclass restriction on this 
class.  I then create an instance of the class with no restriction.  I 
do not understand why the reasoner does not complain that an instance of 
the class exists without this restriction.    (03)

Maybe this is easier to understand with a specific example:    (04)

Two classes: Water and Fish.
Restriction:  Fish subclassOf livesIn some Water
Two instances:  Goldfish type Fish, River some Water.    (05)

I do not understand the following:    (06)

Goldfish is a member of Fish.
Fish implies (livesIn some Water)    (07)

I have /*not */implemented the restriction but the reasoner does not 
complain.  Goldfish is a member of the class and therefore the 
restriction is implied.  The reasoner does not seem to see things this way.    (08)

Any help would be appreciated.    (09)

Thanks in advance,    (010)

Mark    (011)

>       (012)

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