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<br>
Thanks for pointing this out Bob,<br>
<br>
I find it hard to follow without knowing what LinkBase is for. Are they
trying to create an ontology that 'does anything'. The definition on
the Language and Communication website says:<br>
<blockquote><i> LinKBase® is an expansive medical knowledge base that
provides the "intelligence" used by all L&C applications.</i><br>
</blockquote>
I read this as "an ontology that will do anything our customers need". <br>
<br>
He is arguing between two approaches. One may be suitable for one
purpose and another suitable for another purpose - even though it is
less elegant.<br>
<br>
There is no 'correct' model to be discovered here only a model that is
useful for doing X.<br>
<br>
Without a constrained definition of what X is there are no criteria to
say whether what is proposed is good. "Anything" is not a good
definition of X. Once you have an ontology for doing X you may discover
it is pretty good at doing Y but it will never be able to do
everything. Nothing can do everything - which is a pretty good argument
for very small ontologies :)<br>
<br>
A model is merely a view onto reality from a particular perspective -
the perspective that seems important right now.<br>
<br>
Large ontologies are things that people have spent a great deal of time
and money on and are therefore expected to be applicably in many ways.
This doesn't mean that they actually are applicable in many ways it
just means it would be nice if they were.<br>
<br>
Just my thoughts and probably off the topic of OWL usage. I am sure, as
OWL goes, what is discussed is all technically true.<br>
<br>
All the best,<br>
<br>
Roger<br>
<br>
<br>
Bob Morris wrote:
<blockquote cite="mid4512C64E.8090105@cs.umb.edu" type="cite">Several
of you have seen this interesting piece at its point of origin
<br>
<br>
-------- Original Message --------
<br>
Subject: [seek-kr-sms] Modeling large scale ontologies in OWL:
Unmet needs (fwd)
<br>
Date: Thu, 21 Sep 2006 09:23:43 -0700 (PDT)
<br>
From: Shawn Bowers <a class="moz-txt-link-rfc2396E" href="mailto:sbowers@ucdavis.edu"><sbowers@ucdavis.edu></a>
<br>
To: <a class="moz-txt-link-abbreviated" href="mailto:seek-kr-sms@ecoinformatics.org">seek-kr-sms@ecoinformatics.org</a>
<br>
<br>
<br>
<br>
This is a good explanation of a current problem in OWL, and relevant to
<br>
SEEK KR/SMS. This problem haso been addressed in OWL 1.1 via qualified
<br>
cardinality restrictions. Interestingly, I believe OBOE was recently
<br>
criticized for using the same property name with two distinct domains
(the
<br>
"hasSubject" property), however, this email argues that this is often a
<br>
useful approach.
<br>
<br>
<br>
-shawn
<br>
<br>
<br>
---------- Forwarded message ----------
<br>
Date: Wed, 20 Sep 2006 16:25:33 +0200
<br>
From: David Decraene <a class="moz-txt-link-rfc2396E" href="mailto:David@landcglobal.com"><David@landcglobal.com></a>
<br>
To: <a class="moz-txt-link-abbreviated" href="mailto:public-semweb-lifesci@w3.org">public-semweb-lifesci@w3.org</a>
<br>
Subject: Modeling large scale ontologies in OWL: Unmet needs
<br>
Resent-Date: Thu, 21 Sep 2006 04:57:52 +0000
<br>
Resent-From: <a class="moz-txt-link-abbreviated" href="mailto:public-semweb-lifesci@w3.org">public-semweb-lifesci@w3.org</a>
<br>
<br>
<br>
I would like to bring to discussion/debate what I believe is a flaw in
the
<br>
design of the OWL web ontology language, at least if OWL will also
serve a
<br>
purpose in representing large scale ontologies. I'll start the
discussion
<br>
by listing some general examples of OWL 'properties' from the OWL
<br>
tutorials: HasFinger, HasSpouse, HasTopping, HasVintageYear,
HasBrother,
<br>
HasParent, HasUncle, HasMaker, HasSugar, etc ... We have a problem with
<br>
this, seeing that these are not properties, but concatenated Property -
<br>
Target combinations. For a large scale (formal) ontology, imagine the
<br>
amount of duplication would occur if we would treat every parthood
<br>
relation as such; HasFinger, HasToe, HasNail, HasHair, HasSkin,
HasVein,
<br>
HasCell, HasBone, HasMuscle, etc... In large scale ontologies, one link
<br>
should suffice, HasPart, and whether the part is a finger, toe, nail,
<br>
muscle or anything else is not a task for the property to describe, but
<br>
for the target, e.g. the ISA hierarchy where the respective parts are
<br>
situated in. Now this might seem trivial, and it might seem that OWL
<br>
allows the second approach as well, but the fact is that OWL propagates
<br>
this line of thought in how properties should be constructed and
<br>
restricted: Some of the existing expressivity of OWL (mainly: assigning
<br>
cardinalities) can not be applied if we decide to generalize property
<br>
types (formal modeling) to represent the nature of the relation, e.g.
<br>
without a description of what the target is (which is a task for the
<br>
target hierarchy).
<br>
<br>
Lost expressivity: cardinality. In OWL optional properties can be used
by
<br>
setting mincardinality to 0: <Hand> Has6thFinger mincardinality 0
See how
<br>
in the above example we do NOT state a target. As a matter of fact the
<br>
above named property only has a meaning when the range is specified, in
<br>
this case the range might be <6th finger>. So we can use optional
<br>
properties, but only if we create a unique property for every property
-
<br>
target combination. In formal ontology you could express this relation
on
<br>
a general level of parthood: <Hand> HasPart <6thfinger>,
cardinality 0.
<br>
This is not possible in OWL.
<br>
<br>
In OWL absence of properties can be modeled by setting cardinality to
0:
<br>
<Undiagnosed hyperbilirubinemia> IsDiagnosisParticipant
cardinality 0
<br>
<Untreated hyperbilirubinemia> IsTreatmentParticipant cardinality
0 Again
<br>
in these examples we do NOT state the target, and again these above
stated
<br>
examples might be referring to anything, the only way we (and a
reasoner)
<br>
are able to figure that the properties are about <Diagnosis> and
<br>
<Treatment> is if we set the range of those properties as such.
In formal
<br>
ontology you would express this relation on a general level of
<br>
participation: <Undiagnosed hyperbilirubinemia> IsParticipantOf
<br>
<Diagnosis> Cardinality 0 <Untreated hyperbilirubinemia>
IsParticipantOf
<br>
<Treatment> Cardinality 0
<br>
<br>
Conclusion: OWL offers great expressivity, but only IF we use the above
<br>
mentioned approach of proliferating redundant properties at a large
scale.
<br>
This is not a luxury we have in (formal) modeling of large scale
<br>
ontologies. As an example, the core domain of LinkBase (our inhouse
<br>
formal, medicine-oriented ontology) exists of about 700.000 concepts
<br>
(classes) which are related to each other with more than 700.000
relation
<br>
instantiations. The OWL approach would lead to hundred thousands of
<br>
properties, which in many ways would duplicate the classhierarchy.
<br>
<br>
It would be great to receive some feedback on this matter.
<br>
<br>
David Decraene
<br>
PH.D. BioMedical sciences/Ontology modeller.
<br>
Language and Computing
<br>
<br>
<br>
<br>
<br>
<br>
_______________________________________________
<br>
Seek-kr-sms mailing list
<br>
<a class="moz-txt-link-abbreviated" href="mailto:Seek-kr-sms@ecoinformatics.org">Seek-kr-sms@ecoinformatics.org</a>
<br>
<a class="moz-txt-link-freetext" href="http://mercury.nceas.ucsb.edu/ecoinformatics/mailman/listinfo/seek-kr-sms">http://mercury.nceas.ucsb.edu/ecoinformatics/mailman/listinfo/seek-kr-sms</a>
<br>
<br>
<br>
</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
-------------------------------------
Roger Hyam
Technical Architect
Taxonomic Databases Working Group
-------------------------------------
<a class="moz-txt-link-freetext" href="http://www.tdwg.org">http://www.tdwg.org</a>
<a class="moz-txt-link-abbreviated" href="mailto:roger@tdwg.org">roger@tdwg.org</a>
+44 1578 722782
-------------------------------------
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