[topicmapmail] instance-of relationship

Fri, 5 Sep 2003 18:09:55 +0100

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Kathy
=20
Two points to make in response to your post:
=20
1) Can an individual be a class? (or - Can a class be an individual?)
=20
First, I (and the topic maps paradigm) do not accept that an individual
cannot be a class. True, there are deep and difficult philosophical,
logical and mathematical issues over what happens if you allow a class
to act as an individual without restriction, since to do so can lead to
logical paradoxes. However, it is quite clear that in ordinary language
(and ordinary thinking) as well as in logic and mathematics, it is often
necessary to talk of classes of classes, which are themselves classes,
and whose members (instances) are classes. Are these classes individuals
or not? I guess that depends on what you mean by individual, but
certainly they are instances - namely instances of the class of classes
to which they belong.
=20
Given this, what are we to do about the logical paradoxes?
=20
Many different approaches are possible. Russell (who was the first
clearly to define the nature of the paradoxes involved) developed his
"Theory of Types" to deal with this issue. (See
http://planetmath.org/encyclopedia/AxiomOfReducibility.html )=20
=20
Murray's preferred approach is to distinguish the "contexts" in which a
given subject acts as a class from the "contexts" in which it acts as an
instance.
=20
A third approach is described by Matthew West in his paper Metaphysical
Notes (http://www.nist.gov/sc4/wg_qc/wg10/current/n282/wg10n282.pdf ).=20
=20
All three of these approaches fall somewhere between the draconian "an
individual cannot be a class" approach that you cite, and the
libertarian "things can be both individuals and classes freely and
without restriction" approach that is adopted both by Topic Maps and by
Semantic Networks.
=20
=20
2) In your example you are, I think, confused when you state
=20
> if I want to type a topic, e.g. camera being a kind of device. ...
"camera" becomes an instance of the type (class) device
=20
No. It becomes a subclass of the class device.
=20
camera subclassOf device
=20
> But by doing so I don't think of camera being an individual.
=20
Fine, for the moment - but see below.
=20
> An individual is my_camera.=20
=20
Agreed - and therefore we have:
=20
my_camera instanceOf camera
camera subclassOf device
=20
from which can be inferred:
=20
my_camera instanceOf device.
=20
So far so good: no problem, no complexity and no paradox.
=20
If we now go back to the part of your model that I took issue with:
=20
> if I want to type a topic, e.g. camera being a kind of device.
=20
You said: ... "camera" becomes an instance of the type (class) device
=20
I say: ...  "camera" is an instance of the class "type-of-device"
=20
camera instanceOf type-of-device=20
=20
This gives us the following complete set of statements:
=20
my_camera instanceOf camera
camera subclassOf device
my_camera instanceOf device.
camera instanceOf type-of-device=20
=20
If you wish, you could for logical completeness (though the statement in
itself is not that useful) assert:
=20
device instanceOf type-of-device
=20
=20
Hope this helps
=20
Best regards
=20
Daniel
=20
-----Original Message-----
From: Lieberknecht, Katharina
[mailto:Katharina.Lieberknecht@astrium-space.com]=20
Sent: 03 September 2003 19:23
To: 'topicmapmail@infoloom.com'
Subject: [topicmapmail] instance-of relationship
=20
Hi all,=20
I know the relationship "instance-of" from KR with semantic networks=20
where it is used to define the relationship between a class and an
individual of=20
that class. One feature of an individual, as I know it, is that it
cannot play the=20
role of a class.=20
Does the "instance-of"-relationship or the
"class-instance"-relationship, respectively=20
have different semantics in semantic networks and topic maps?=20
Or is it just a naming problem? And the term "instance" implies that=20
it is an "individual"?=20
My interpretation at the moment is this:=20
The ISO standard says that the semantic between a topic-type and its
instance is=20
that of a "class" and its "instance" and can therewith be equally
expressed=20
with a "instance-of" relationship.=20
Since the creation of topic-types and its instances is essential
(especially with associations), the relationship=20
became a "built-in" feature in the XTM-notation as the <instanceOf>
element.=20
So I have to use this element if I want to type a topic, e.g. camera
being a kind of=20
device. By doing so "camera" becomes an instance of the type (class)
device.=20
But by doing so I don't think of camera being an individual. An
individual is my_camera.=20
So, do I have to (or can I) establish another relationship conveying the
semantic=20
between a class and individuals of this class.=20
Is it possible / correct to model something like:
device [role:class] "instance-of" [role:instance] camera [role:class]
"class-individual" [role:individual] my_camera=20
Greetings and many thanks for comments=20
Kathy=20
=20

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<body lang=3DEN-US link=3Dblue vlink=3Dpurple =
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<div class=3DSection1>

<p class=3DMsoNormal><st2:GivenName><font size=3D2 color=3Dnavy =
face=3DArial><span
 =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>Kathy</span></fon=
t></st2:GivenName><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'><o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Two points to make in response to =
your
post:<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

1) Can an individual be a class? =
(or &#8211; Can a class be an =
individual?)<o:p></o:p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

First, I (and the topic maps =
paradigm) do
not accept that an individual cannot be a class. True, there are deep =
and
difficult philosophical, logical and mathematical issues over what =
happens if
you allow a class to act as an individual without restriction, since to =
do so
can lead to logical paradoxes. However, it is quite clear that in =
ordinary
language (and ordinary thinking) as well as in logic and mathematics, it =
is
often necessary to talk of classes of classes, which are themselves =
classes,
and whose members (instances) are classes. Are these classes
individuals or not? I guess that depends on what you mean by individual, =
but
certainly they are instances &#8211; namely instances of the class of =
classes
to which they belong.<o:p></o:p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Given this, what are we to do about =
the
logical paradoxes?<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

Many different approaches are =
possible. <st2:GivenName>Russell</st2:GivenName> (who
was the first clearly to define the nature of the paradoxes involved) =
developed
his &#8220;Theory of Types&#8221; to deal with this issue. (See <a
href=3D"http://planetmath.org/encyclopedia/AxiomOfReducibility.html">http=
://planetmath.org/encyclopedia/AxiomOfReducibility.html</a>
) <o:p></o:p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><st1:City><st1:place><st2:Sn><font size=3D2 =
color=3Dnavy
   face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>Murray</span></fo=
nt></st2:Sn></st1:place></st1:City><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'>&#8217;s preferred approach is to distinguish the
&#8220;contexts&#8221; in which a given subject acts as a class from the
&#8220;contexts&#8221; in which it acts as an =
instance.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

A third approach is described by =
<st1:PersonName><st2:GivenName>Matthew</st2:GivenName> =
<st2:Sn>West</st2:Sn></st1:PersonName> in his paper Metaphysical =
Notes
(<a =
href=3D"http://www.nist.gov/sc4/wg_qc/wg10/current/n282/wg10n282.pdf">htt=
p://www.nist.gov/sc4/wg_qc/wg10/current/n282/wg10n282.pdf</a>
). <o:p></o:p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><span class=3DGramE><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>All three of =
these
approaches fall somewhere between the draconian &#8220;an individual =
cannot be
a class&#8221; approach that you cite, and the libertarian &#8220;things =
can be
both individuals and classes freely and without restriction&#8221; =
approach that
is adopted both by Topic Maps and by Semantic =
Networks.</span></font></span><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'><o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>2) In your example you are, I =
think,
confused when you state<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

&gt; if I want to type a =
topic,
e.g. camera being a kind of device. &#8230; &quot;camera&quot; becomes an instance of the type =
(class) device<o:p></o:p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

No. It becomes a subclass of the =
class
device.<o:p></o:p>

<p style=3D'margin:0cm;margin-bottom:.0001pt'><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial'><o:p>&nbsp;</o:p></span></fo=
nt></p>

<p class=3DMsoNormal><span class=3DGramE><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>camera</span></fo=
nt></span><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'> <span class=3DSpellE>subclassOf</span> =
device<o:p></o:p></span></font></p>

<p style=3D'margin:0cm;margin-bottom:.0001pt'><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial'><o:p>&nbsp;</o:p></span></fo=
nt></p>

<p style=3D'margin:0cm;margin-bottom:.0001pt'><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial'>&gt; But by doing so I =
don't think
of camera being an individual.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Fine, for the moment &#8211; but =
see
below.<o:p></o:p></span></font></p>

<p style=3D'margin:0cm;margin-bottom:.0001pt'><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial'><o:p>&nbsp;</o:p></span></fo=
nt></p>

<p style=3D'margin:0cm;margin-bottom:.0001pt'><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial'>&gt; An individual is <span
class=3DSpellE>my_camera</span>.</span></font> <o:p></o:p></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Agreed &#8211; and therefore we =
have:<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><span class=3DSpellE><span class=3DGramE><font =
size=3D2
color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'>my_camera</span></font></span></span><font size=3D2 =
color=3Dnavy
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'> <span
class=3DSpellE>instanceOf</span> camera<o:p></o:p></span></font></p>

<p class=3DMsoNormal><span class=3DGramE><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>camera</span></fo=
nt></span><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'> <span class=3DSpellE>subclassOf</span> =
device<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><span class=3DGramE><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>from</span></font=
></span><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'> which can be inferred:<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><span class=3DSpellE><span class=3DGramE><font =
size=3D2
color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'>my_camera</span></font></span></span><font size=3D2 =
color=3Dnavy
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'> <span
class=3DSpellE>instanceOf</span> device.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>So far so good: no problem, no =
complexity
and no paradox.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>If we now go back to the part of =
your
model that I took issue with:<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

&gt; if I want to type a =
topic, e.g.
camera being a kind of device.<o:p></o:p></f=
ont>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>You said: </span></font><font =
size=3D2
face=3DArial><span style=3D'font-size:10.0pt;font-family:Arial'>&#8230; =
&quot;<span
class=3DGramE>camera</span>&quot; becomes an instance of the type =
(class) device<font
color=3Dnavy><span =
style=3D'color:navy'><o:p></o:p></span></font></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>I say: &#8230;<span
style=3D'mso-spacerun:yes'>&nbsp; </span>&#8220;<span =
class=3DGramE>camera</span>&#8221;
is an instance of the class =
&#8220;type-of-device&#8221;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><span class=3DGramE><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>camera</span></fo=
nt></span><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'> <span class=3DSpellE>instanceOf</span> type-of-device =
<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>This gives us the following =
complete set of
statements:<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><span class=3DSpellE><span class=3DGramE><font =
size=3D2
color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'>my_camera</span></font></span></span><font size=3D2 =
color=3Dnavy
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'> <span
class=3DSpellE>instanceOf</span> camera<o:p></o:p></span></font></p>

<p class=3DMsoNormal><span class=3DGramE><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>camera</span></fo=
nt></span><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'> <span class=3DSpellE>subclassOf</span> =
device<o:p></o:p></span></font></p>

<p class=3DMsoNormal><span class=3DSpellE><span class=3DGramE><font =
size=3D2
color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'>my_camera</span></font></span></span><font size=3D2 =
color=3Dnavy
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'> <span
class=3DSpellE>instanceOf</span> device.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><span class=3DGramE><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>camera</span></fo=
nt></span><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'> <span class=3DSpellE>instanceOf</span> type-of-device =
<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>If you wish, you could for logical
completeness (though the statement in itself is not that useful) =
assert:<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><span class=3DGramE><font size=3D2 color=3Dnavy =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>device</span></fo=
nt></span><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'> <span class=3DSpellE>instanceOf</span> =
type-of-device<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><st2:GivenName><font size=3D2 color=3Dnavy =
face=3DArial><span
 =
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>Hope</span></font=
></st2:GivenName><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy'> this helps<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy;mso-no-proof:yes'>Best =
regards<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy;mso-no-proof:yes'><o:p>&nbsp;</o:p></=
span></font></p>

<p class=3DMsoNormal><st2:GivenName><font size=3D2 color=3Dnavy =
face=3DArial><span
 =
style=3D'font-size:10.0pt;font-family:Arial;color:navy;mso-no-proof:yes'>=
Daniel</span></font></st2:GivenName><font
size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;
color:navy;mso-no-proof:yes'><o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy;mso-no-proof:yes'><o:p>&nbsp;</o:p></=
span></font></p>

<p class=3DMsoNormal style=3D'margin-left:36.0pt'><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma'>-----Original =
Message-----<br>
<b><span style=3D'font-weight:bold'>From:</span></b> =
</span></font><st2:GivenName><font
 size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'>Lieberknecht</span></font><=
/st2:GivenName><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'>, =
</span></font><st2:GivenName><font
 size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'>Katharina</span></font></st=
2:GivenName><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'>
[mailto:Katharina.Lieberknecht@astrium-space.com<span class=3DGramE>] =
<br>
<b><span style=3D'font-weight:bold'>Sent</span></b></span><b><span
style=3D'font-weight:bold'>:</span></b> </span></font><st1:date =
Month=3D"9" Day=3D"3"
Year=3D"2003"><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:
 Tahoma'>03 September 2003</span></font></st1:date><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma'> </span></font><st1:time =
Hour=3D"19"
Minute=3D"23"><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:
 Tahoma'>19:23</span></font></st1:time><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma'><br>
<b><span style=3D'font-weight:bold'>To:</span></b> =
'topicmapmail@infoloom.com'<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> [topicmapmail] =
instance-of
relationship</span></font><o:p></o:p></p>

<p class=3DMsoNormal style=3D'margin-left:36.0pt'><font size=3D3
face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p style=3D'margin-left:36.0pt'><font size=3D2 face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial'>Hi all,</span></font> <o:p></o:p></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. <o:p></o:p>

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;? =
<o:p></o:p>

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. <o:p></o:p>

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
<o:p></o:p>

<p style=3D'margin-left:36.0pt'><font size=3D2 face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial'>Greetings and many thanks for <span =
class=3DGramE>comments<font
size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt;font-family:"Times New Roman"'>
<br>
</span></font></span></span></font><st2:GivenName><span =
class=3DGramE><font
 size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial'>Kathy</span></font></span></=
st2:GivenName>
<o:p></o:p></p>

<p class=3DMsoNormal =
style=3D'mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:
12.0pt;margin-left:36.0pt'><font size=3D3 face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>

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