Charles, (01)
You can view a thesaurus as a term taxonomy enhanced with synonymy,
homonymy, associations (no real relations, just associated terms),
perhaps preferred terms, and scope notes. The primary or privileged
parent-child relation (broader_than, narrower_than) is
generalization/specialization, and is a subsumption relation -- if you
view the class of all things referred to by the narrower term as a
subset of all the things referred to by the broader term. So in that
sense, it is more expressive semantically -- though in the weaker
semantics of terms. (02)
A taxonomy can be sound or flawed (I use strong vs. weak), and term or
concept based -- with perhaps the usual caveat about concepts being
placeholders for real world entities, assuming you are a philosophical
realist. (03)
Strong taxonomy:
For concepts, if the privileged parent-child relation is indeed
subclass (meaning that to be a subclass a node/entity has to possess a
necessary distinguishing property, i.e., distinguish it from its parent
but also its siblings), or for terms, if the relation is narrower_than,
then it is a strong taxonomy. So, really the relation is subsumption. (04)
Weak taxonomy:
All one can say about a weak taxonomy is that the parent-child relation
is subclassification_of, since nearly arbitrary nodes may appear
anywhere or the parent-child relation is inconsistent across the
taxonomy. Your typical file-folder structure is thereby a weak
taxonomy. I find it nearly synonymous with "arbitrary hierarchy". (05)
The briefing from the Ontolog talk last Jan 19/26 2006 goes through
this, starting from the Ontology Spectrum slide: "What is an ontology?
- A Briefing on the Range of Semantic Models"
http://ontolog.cim3.net/cgi-bin/wiki.pl?ConferenceCall_2006_01_12. (06)
Thanks,
Leo (07)
_____________________________________________
Dr. Leo Obrst The MITRE Corporation, Information Semantics
lobrst@xxxxxxxxx Center for Innovative Computing & Informatics
Voice: 703-983-6770 7515 Colshire Drive, M/S H305
Fax: 703-983-1379 McLean, VA 22102-7508, USA (08)
-----Original Message-----
From: ontology-summit-bounces@xxxxxxxxxxxxxxxx
[mailto:ontology-summit-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Charles
D Turnitsa
Sent: Tuesday, January 23, 2007 10:15 AM
To: Ontology Summit 2007 Forum
Subject: Re: [ontology-summit] Defining "ontology" (09)
Leo, (010)
Thanks for the response. I just took a look at your slide, and I find
myself a little surprised that you place a thesaurus at a higher level
of
expressiveness than a taxonomy, but perhaps this is another sand trap
of
nomenclature... (011)
I have, over the past year, drawn one of the major differences between
a
thesaurus and taxonomy at the fact that a thesaurus shows things like
synonym and homonym relationships, but these tend to focus on the term
(or
symbol) level, whereas a taxonomy tends to organize things into a
subsumption hierarchy, which shows a growth of meaning from a root
entity
to any leaf. In my understanding, the taxonomy tends to have a greater
capacity to show meaning, than a thesaurus. (012)
Chuck (013)
ontology-summit-bounces@xxxxxxxxxxxxxxxx wrote on 01/22/2007 09:20:00
PM: (014)
> Charles,
>
> I agree with you. A number of us through the years have come up with
> similar ontology continuums or spectrums. I prefer my Ontology
> Spectrum*, but that's natural, I guess. It was developed over time
> to act as an educational aid. I found that many folks understood
> notions such as taxonomies, database schemas, UML models, but they
> didn't know how these related to the new kid on the block,
> ontologies. Was a thesaurus an ontology? No. Was a UML model: no,
> not yet. And term vs. concept (placeholder for real world referent)
> is a crucial distinction. The former is a word/phrase (string,
> utterance) that indexes the latter, which is a representation of the
> meaning of that term (at least approximately). The important point
> is that these concepts/placeholders are meant to stand in for real
> world referents, since ontology is about the things of the world. I
> also attach a newer slide that tries to show those distinctions,
> along with their typical use cases:
OntologySpectrumApplication-Obrst06.jpg.
>
> Thanks,
> Leo
>
> *If you look at the current Wikipedia article on the subject, it's
> not completely accurate:
http://en.wikipedia.org/wiki/Semantic_spectrum
> . I independently developed the Ontology Spectrum in Fall, 1999, and
> it really represents one dimension, though it is depicted diagonally
> (for increased space) as though it were two dimensional: the one
> dimension is in terms of expressivity of the model. Also the 4 way
> stations of taxonomy, thesaurus, conceptual model, and logical
> theory are semantic models; that is why I don't include glossaries,
> term lists, etc., directly -- they are not models but are human
> language lists and definitions. Mike Uschold, Mike Gruninger, and
> Chris Welty and I have talked about this topic of the co-invention
> of the semantic/ontology spectrum for quite some time. Personally, I
> prefer my Ontology Spectrum because I overlay onto the specific
> models additional information, such as the kind of parent-child
> relation, related database and modeling languages, and logic
> information. But all of these ontology spectrum/semantic continuums
> are sound: they represent the best distillations of solid
> generalizations especially good for educational purposes.You are
> probably referring to the presentations I gave at Ontolog last Jan
> 19/26 2006: "What is an ontology? - A Briefing on the Range of
Semantic
Models
> ", http://ontolog.cim3.net/cgi-bin/wiki.pl?ConferenceCall_2006_01_12.
>
> _____________________________________________
> Dr. Leo Obrst The MITRE Corporation, Information Semantics
> lobrst@xxxxxxxxx Center for Innovative Computing & Informatics
> Voice: 703-983-6770 7515 Colshire Drive, M/S H305
> Fax: 703-983-1379 McLean, VA 22102-7508, USA
> (015)
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