Garz,
I am not quite clear about the question, and the distinctions you are
making. Every subclass merely picks out of some parent class instances
that have specific properties. So you cannot have in a subclass properties
that are not also in the parent class, but you can *require* that the
instances of the subclasses have a specific property, even if that property
is not "mentioned" (i.e. not required) for every instance of the parent
class. (01)
The term "intersection" is usually used to refer to an intersection of
classes - the intersection is the class of entities, each of which is an
instance of both parent classes. That intersection is a subclass of each of
the parent classes. If you have a class of "RedThings" (anything that is
red) and a class of "Wines" and you define a class of "RedWines" it could be
a subclass of both RedThings and of "Wines", and would be the same as the
intersection of "RedThings" and "Wines", unless you also add other
restrictions to the "RedWines" class. [[ this is a bad example, because
colors are too heterogeneous in application for "RedThings" to be a useful
class]]. You seem to be using "intersection" in a different sense. (02)
Perhaps you could give a more specific example of what you would like to
do. (03)
Pat (04)
Patrick Cassidy
MICRA, Inc.
908-561-3416
cell: 908-565-4053
cassidy@xxxxxxxxx (05)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of garz
> Sent: Friday, July 24, 2009 12:35 PM
> To: ontolog-forum@xxxxxxxxxxxxxxxx
> Subject: [ontolog-forum] When to use pure subclassing and when to use
> subclassing by intersecting
>
> Hi,
>
> i'm trying to create an ontology and there is a problem that i have in
> understanding the difference between a pure subclass and a subclass
> defined as intersection. my own explanation for this is the following:
>
> a subclass defined as intersection relates to the properties the
> superclass has and constraints them. for example redwine constraints
> the
> property color of the superclass wine by constraining its value to red.
> redwine is like an aspect or a view on a class, in this case on the
> aspect color. or its like an alias picking a subset out of the related
> superclass. a class defined that way introduces a new concept or term
> by
> just using the already existing, its not capable of creating new
> content, so to speak.
>
> a pure subclass should then be used, if there is something new to it,
> represented as a property that isnt mentioned in the superclass and the
> subclass is free to introduce this property or not. if the property
> already was in the superclass, a subclass defined by intersection would
> be sufficient.
>
> am i correct with this thinking? i dont really get it. or is
> intersection always applicable, but in this case i really dont
> understand the sense behind it. plz enlighten me.
>
> regards
>
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