[topicmapmail] instance-of relationship

Wed, 3 Sep 2003 20:23:20 +0200

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Hi all,

I know the relationship "instance-of" from KR with semantic networks
where it is used to define the relationship between a class and an
individual of 
that class. One feature of an individual, as I know it, is that it cannot
play the
role of a class.

Does the "instance-of"-relationship or the "class-instance"-relationship,
respectively
have different semantics in semantic networks and topic maps?
Or is it just a naming problem? And the term "instance" implies that
it is an "individual"?

My interpretation at the moment is this:
The ISO standard says that the semantic between a topic-type and its
instance is
that of a "class" and its "instance" and can therewith be equally expressed
with a "instance-of" relationship.
Since the creation of topic-types and its instances is essential (especially
with associations), the relationship
became a "built-in" feature in the XTM-notation as the <instanceOf> element.
So I have to use this element if I want to type a topic, e.g. camera being a
kind of
device. By doing so "camera" becomes an instance of the type (class) device.
But by doing so I don't think of camera being an individual. An individual
is my_camera.

So, do I have to (or can I) establish another relationship conveying the
semantic
between a class and individuals of this class. 
Is it possible / correct to model something like:
device [role:class] "instance-of" [role:instance] camera [role:class]
"class-individual" [role:individual] my_camera

Greetings and many thanks for comments
Kathy

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<P><FONT SIZE=3D2 FACE=3D"Arial">Hi all,</FONT>
</P>

I know the relationship =
&quot;instance-of&quot; from KR with semantic networks
 where it is used to define the =
relationship between a class and an individual of 
 that class. One feature of an =
individual, as I know it, is that it cannot play the
 role of a class.

Does the =
&quot;instance-of&quot;-relationship or the =
&quot;class-instance&quot;-relationship, respectively
 have different semantics in semantic =
networks and topic maps?
 Or is it just a naming problem? And =
the term &quot;instance&quot; implies that
 it is an =
&quot;individual&quot;?

My interpretation at the moment is =
this:
 The ISO standard says that the =
semantic between a topic-type and its instance is
 that of a &quot;class&quot; and its =
&quot;instance&quot; and can therewith be equally expressed
 with a &quot;instance-of&quot; =
relationship.
 Since the creation of topic-types and =
its instances is essential (especially with associations), the =
relationship
 became a &quot;built-in&quot; feature =
in the XTM-notation as the &lt;instanceOf&gt; element.
 So I have to use this element if I =
want to type a topic, e.g. camera being a kind of
 device. By doing so =
&quot;camera&quot; becomes an instance of the type (class) =
device.
 But by doing so I don't think of =
camera being an individual. An individual is my_camera.

So, do I have to (or can I) establish =
another relationship conveying the semantic
 between a class and individuals of =
this class. 
 Is it possible / correct to model =
something like: 
device [role:class] &quot;instance-of&quot; [role:instance] camera =
[role:class] &quot;class-individual&quot; [role:individual] =
my_camera

<P><FONT SIZE=3D2 FACE=3D"Arial">Greetings and many thanks for =
comments</FONT>
<BR><FONT SIZE=3D2 FACE=3D"Arial">Kathy</FONT>
</P>
<BR>
<BR>
<BR>

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