So true. There is no infinite wisdom,
only what is known from one perspective at one place and one point in time.
Joyce W. Koeneman
Digital Librarian and Head Tech Services
National Transportation Library
202.366.4203
joyce.koeneman@xxxxxxx
-----Original Message-----
From:
ontac-forum-bounces@xxxxxxxxxxxxxx [mailto:ontac-forum-bounces@xxxxxxxxxxxxxx] On Behalf Of West, Matthew R SIPC-DFD/321
Sent: Friday, November 18, 2005
7:06 AM
To: ONTAC-WG General Discussion
Subject: RE: [ontac-forum] Some
thoughts on hub ontology and merging sources
I think that it is useful
to be clear about what is possible about merging ontologies and what is not
possible.
I appreciate that
intuitively you would think that (taking a realist position) there is one
universe out there, so it should not be beyond the wit of man to come up with
one ontology of that universe. Unfortunately, even with one universe it is at
least theoretically possible to come up with an infinite number of ontologies -
almost certainly none of them truly correct, but possibly several of them being
accurate enough to be useful. So in practice it is relatively comforting that
there are relatively few actually around.
So what are the barriers
to merging the relatively few we have?
Philosophers working in
this area have identified a number of choices that charaterise a particular
ontology, these include:
1. Are physical objects
wholly present at each point in time, and pass through time, or are they
extended in time and have temporal parts?
2. Can two distinct
individuals have the same extent (spatially and temporally)?
Merging ontologies will
only be possible where the same choices have been made for these (and perhaps
other) things. Between ontologies that have made different choices, the
ontologies can be expected to differ in their account of the same real world
phenomena in a way that cannot be simply merged.
What you can do about
ontologies with such different foundations is map between them. You could of
course make a choice, but I think this would be a mistake, since I believe that
the different choices that can be made each have benefits in different
circumstances, such that the greatest utility is gained by being able to choose
- just as one can choose the model of gravity you wish to use for some
purpose.
Regards
Matthew West
Reference Data Architecture and Standards Manager
Shell International Petroleum Company Limited
Shell Centre, London SE1 7NA, United Kingdom
Tel: +44 20 7934 4490 Mobile: +44 7796 336538
Email: matthew.west@xxxxxxxxx
http://www.shell.com
http://www.matthew-west.org.uk/
-----Original
Message-----
From:
ontac-forum-bounces@xxxxxxxxxxxxxx [mailto:ontac-forum-bounces@xxxxxxxxxxxxxx]On Behalf Of Cassidy, Patrick J.
Sent: 18 November 2005 09:10
To: ONTAC-WG General Discussion
Subject: RE: [ontac-forum] Some
thoughts on hub ontology and merging sources
Gary Berg-Cross
has articulated a number of legitimate issues concerning the method for
moving toward a Common Semantic Model. His points are diverse,
and think it best to respond to some of these points by
describing my own views -- which may not be those ultimately chosen by
the COSMO-WG as a whole.
(1) Hub? I think
that ultimately one COSMO will best serve the purposes of interoperability, and
for me the question is how to get there -- to start with one upper ontology and
elaborate it by mapping to the multiple KCSs used by ONTACWG members, or to
start with with several competent ontologies, and to merge them. My
suggestion was to try both approaches simultaneously, i.e. in one part to
investigate the potential for merger by formalizing the UMLS semantic network
using each candidate upper ontology separately, and to compare
the resulting fragments of each upper ontology to determine how
closely those parts are related and just how easy a merger would be.
In a second part, the FEA-RMO and DoD Upper taxonomy could also be formalized
with respect to one of the upper ontologies, chosen by some criteria such as
those suggested by Eric Peterson. That is, we would
not prejudge the issue of whether or not to choose one existing hub from
the start, but to gather more information to determine whether a merger
would be so difficult that choosing one existing ontology is the only practical
course. The question of using an existing ontology as a hub for
formalization of includes the question of what criteria would be used to choose
the hub, and any thoughts on that issue would be welcome right now.
Concerning Gary's
feeling that:
>> I don't see how this could be done with merging some existing
ontologies and various people have talked about using UMLS
DOLCE/BFO, SUMO, OpenCyc, ISO 15926, FEA-RMO and the DoD Core Taxonomy.
It is important to
distinguish the formal upper ontologies from the FEA-RMO and DoD Core
taxonomy. The latter two are candidates for formalization with respect to one
of the upper ontologies, they would not serve as upper ontologies on the same
level as the others.
It is not clear a priori
without careful investigation that any one of the potential hubs has everything
that is in all of the others, and does not need supplementation. The formalization
of the UMLS-SN is a non-trivial but tractable test case that should provide
some objective information to help evaluate the candidates and estimate the
difficulty of merger. I am hoping that we can begin discussing specifics soon.
(2) The FEA-RMO and DoD
core taxonomy do indeed have problems if looked at as starting
ontologies. The DoD Core doesn't pretend to be an ontology, and the
FEA-RMO is, as Gary points out, closer to a Reference Model, though expressed
in ontology format. There are nevertheless good reasons to try to connect
these to the UMLS. (a) The FEA-RMO is an active project, which may well
form part of any common ontology ultimately developed for use within that
federal government. There are expectations that the SICoP will help
in some way in the development of that model. The ONTACWG could be
helpful in making recommendations on the best way to formalize the FEA-RMO and
align it with other knowledge representation efforts within the government,
even if much of the work will in fact be done by contractors. I
think it would be unfortunate if we ignored it, since we can bring a broad
perspective that can make ontologies developed from or related to the
FEA-RMO more functional. (b) The DoD core taxonomy is still an active
project, and its purpose is very much similar to that of the COSMO, to create a
hub with which domain taxonomies in DoD can be aligned and related. But
it is not intended to function as an ontology for logical inferencing.
By defining the terms of the DoD Core using concepts from the COSMO, we
can make it more useful for logical inferencing, and the mapping of the DoD
Core will have a multiplicative effect because of its already existing
relations with other taxonomies. If there are hierarchical links in
the DoD core that appear invalid form an inheritance point of view, those links
would not appear in the formalized version, but the individual terms could
still be defined by reference to the COSMO. So the lack of formality
of the DoD Core would make the precise formalization more time-consuming, but
would not affect the formalized version, which would have only valid
relations Combined with the UMLS-SN, these two knowledge
classifications provide a diverse set of topics to serve as test cases for
building a COSMO and defining domain knowledge classifications by means of the
COSMO. To be feasible for a volunteer group yet broad enough to
provide a realistic test of the potential for semantic integration, I think
that this set of knowledge classifications contains the proper balance of
complexity and restricted subject matter, and they also relate directly to the
purpose of the SICoP, the parent of the ONTACWG.
(3) The ANSI X3/T2
Ad hoc group on ontology standards:
I
participated in the activity of this group until it faded away around 1998 or
so. As I recall, there were some productive discussions of issues,
but at least one proposal to obtain funding for the activity was
rejected. In the absence of support, it was not possible for participants
to spend enough time to resolve the very complex technical issues, and
participants returned to work on the projects for which they could get
funding. Neither OpenCyc nor SUMO nor DOLCE were available at that
time.
Another smaller project was funded by the Klaus Tschira foundation, to
bring together 20 or so ontologists for two weeks in 1998 to come to agreement
on the structure of the topmost levels of an upper ontology. Most (not
all) participants seemed to think that useful progress was made, but that a lot
more additional work was needed. I do not think that a formal report was
prepared with details of the agreements reached.
A
later effort, the IEEE-SUO project (2001 - present), did get some financial
support, and the SUMO ontology was created from that. The SUMO had some
input from the IEEE group, but was mostly built in-house by Teknowledge.
The absence of funding for anyone outside of Teknowledge left in place the
same problems that bedeviled the ANSI group, namely that the concerns of multiple
communities could not be addressed effectively, and the resulting
ontology represented the views predominantly of a small group, who of necessity
had to move forward quickly to provide the deliverables, regardless of whether
external participants agreed with the results. This problem was not
primarily a result of any lack of interest of the Teknowledge builders for
input from the wider community, but was a structural problem resulting from the
amount and distribution of funding. This project illustrated one major
barrier to agreement -- that in the absence of applications that could
test alternative suggested ontological representations, and without a mechanism
for efficiently including alternative representations, an ontology, even
built to some extent collaboratively, will inevitably have a lot of elements
that are unsatisfactory to one or another potential user, or lack some they
want.
The
resources that were discussed by the ANSI group then are still valid, but have
been supplemented by additional more developed ontologies and lexical
resources. We have invited participation by all groups, including those
that created those older resources, but as a volunteer group, it is only
possible for us to make substantive efforts using the resources that are of
interest to ONTACWG participants. The WordNet could be investigated
directly if there were any members with a special interest in that
classification. But it will be included in any case indirectly, because
there are mappings of SUMO and Cyc to the WordNet.
There
never has been adequate funding for a substantial collaborative project
involving multiple groups, to find agreement on a common upper ontology, even
though proposals have been made since the time of the ANSI efforts. We can
do what is possible without funding, and hope to encourage agencies to provide
funding at some point soon. The cBio project may help indirectly, if any
people participating in that project include some work with upper ontologies --
or better yet, with the COSMO -- in their proposals.
The
ONTACWG, without funding, can make progress only to a limited extent, but we
have more experience and more examples now to work with than the earlier
projects did. So our task will be easier than the earlier ones. A
plausible goal would be, not to create a common upper ontology de novo, but to
investigate within some limited compass how to choose or adopt one or more
existing upper ontologies to serve as the hub to which multiple domain
knowledge classifications can be related. As mentioned above, I think the
ONTACWG can serve a valuable function by investigating the alternative
approaches of choosing one upper ontology versus merging several. Even
within the limited scope I suggested, this will take a lot of detailed work.
To address the problem of accommodating the views of different users, my
suggestion has been to structure the COSMO so that it will incorporate all
views considered useful by participants. The result is likely to be a
lattice of theories. The precise nature of the lattice that will be
needed is not agreed on at present. Discovering the details of what is
needed to accommodate multiple ontological views will be, I think, one of
the important results of the attempt to formalize the UMLS-SN versus multiple
upper ontologies.
(4) DOLCE and OntoClean
The DOLCE
ontology is one of the upper ontologies that the COSMO-WG will be investigating
as a base for the formalization of the UMLS-SN, and perhaps of the other KCSs
that we are interested in. DOLCE and BFO are the base ontologies that
Olivier Bodenreider and Lowell Vizenor are planning to use in their already
ongoing effort to formalize the UMLS-SN. The other upper ontologies of
interest to ONTACWG participants will be investigated if any of the participants
decide to take the lead in that effort. So the OntoClean method will be
considered as part of the COSMO-WG agenda. There are other formal
methodologies that have been discussed in the literature, such as Michael
Gruninger's "Semantic
integration through invariants" in the Spring
2005 AI magazine. I hope that it will also will be possible to use
such ideas in the COSMO effort.
(5) Other approaches
The
suggestions made thus far do not preclude alternatives. It is, I think,
potentially useful for multiple approaches to be tried at the same time,
because we are in a position to share intermediate results on a regular basis
and take advantage of each other's experience as soon as anything useful is
discovered or proposed, and posted to our Wiki. The ONTACWG is not a
competition, but a collaboration. So the inefficiencies of trying
alternative approaches in traditional research, where one learns of
the results of other work a year or so after a project has been completed,
should not occur in the work we are discussing. If any participants have
a particular interest in trying a specific approach toward relating KCSs to
each other, the ONTACWG environment should provide feedback and support that
will make individual efforts more productive.
The
paper by Doerr, Hunter, and Lagoze starts off expressing a sentiment that is
also shared by myself and a lot of others, that some common top-level ontology
will be needed for accurate semantic interoperability. And some of the
specific observations they make as a result of their study are, I believe,
valid. But as has been pointed out, their proposed merged ontology does
have some problems, and falls far short of the best developed ontologies that
are already available. A one-on-one alignment of that kind may be useful
for applications that are restricted to two or a small group of
communities, but our interest is much broader. I think we can do a
lot better.
Pat
Patrick Cassidy
MITRE Corporation
260 Industrial Way
Eatontown, NJ 07724
Mail Stop: MNJE
Phone: 732-578-6340
Cell: 908-565-4053
Fax: 732-578-6012
Email: pcassidy at mitre.org
From: ontac-forum-bounces@xxxxxxxxxxxxxx
[mailto:ontac-forum-bounces@xxxxxxxxxxxxxx] On
Behalf Of Gary Berg-Cross
Sent: Thursday, November 17, 2005
5:32 PM
To: ontac-forum@xxxxxxxxxxxxxx
Subject: [ontac-forum] Some
thoughts on hub ontology and merging sources
I
wanted to follow up Eric Ps earlier message about a hub approach to building
our common ontology. I think that his questions and issues got side tracked by
the responses to Roy's
"general ontology".
Eric
was curious about "how pervasive those anti-hub feelings really are.
" I'm not of one feeling on this issue, since I think it is complex and
would welcome some discussion of some of it. Eric had particular ideas on Dr.
Sowa's sub-sumption lattice idea, but I haven't heard responses to that and
perhaps others can respond to it.
For
myself, I could imagine going a hub or modular approach depending on the
quality of the hub. I'd have to be convinced that it was doable with our
resources, and would want to know the "seed" for it and the process
or development. I don't see how this could be done with merging some existing
ontologies and various people have talked about using UMLS DOLCE/BFO, SUMO, OpenCyc, ISO 15926, FEA-RMO and the
DoD Core Taxonomy. Assuming even this as a start I have some issues and a
approach to discuss as a strawman.
The
FEA-RMO is an Ontology of a Reference Model and not of an actual domain such
as health. It seems quite hard to connect to this to others.
Also,
the DoD taxonomy, in my opinion, has the degree of problems that Barry and John
pointed out in the "general ontology" so it may not be easy to
assimilate. We might start without trying to merge these in and also might
start with the best 2 or 3 as candidates to seed an effort.
Another point or
question concerns leveraging the experience of past efforts. Back seven years
or more there was an effort by the ANSI Ad Hoc group to
construct a standard, called the Reference Ontology. They had a five-step
approach for the following
1. Upper levels (approx. 100,000 terms): Bring into
correspondence (to align) the terms of a small number of selected large-scale
ontologies (eventual size approx. 100,000 items). Do so inclusively; that is,
create a result in which users can choose which of the component ontologies'
terms they wish to see and use.
2. Domain models (under 2,000 terms each): Link into
this Ontology selected domain-specific ontologies, developed to support
reasoning about time, space, physics, geography, etc. Do so inclusively; allow
the linkage of various different models of time, space, etc.
3. Access tools: Create easy-to-use tools for
Ontology access and extension.
4. Dissemination: Place the resulting Reference
Ontology on the Web, freely available.
5. Theoretical basis: In ongoing work, have a team of
highly qualified individuals comb through the Ontology to find powerful
generalizations, to weed out unnecessary and inconsistent items, and to create
a maximal factoring of the upper levels of the Ontology.
Seems quite similar to what we are
talking about. Whatever happened? Did it fail because it didn't have an upper
ontology?
They listed the following are candidate sources for
terms to be included into their "merged Reference Ontology" and a few
of these (UMLS , CyC) have been mentioned as a base for us too :
·
USC/ISI: Pangloss Ontology SENSUS approx.
70,000 terms, general coverage, little detail, taxonomization supports Natural
Language applications.
·
Princeton:
WordNet approx. 70,000 terms, general coverage, little detail,
taxonomized on Naive Semantics / Cognitive Science principles.
·
CYCorp: Upper portion of CYC ontology approx.
2,500 terms, general coverage, little detail, taxonomized on Naive Semantics /
AI principles. Later additions may include more of the 40,000-odd terms
currently in CYC.
·
EDR: Upper portion of EDR concept ontology
approx. 1,000 terms, general coverage, medium detail, taxonomized for Natural
Language applications. Later additions may include more of the approx. 400,000
terms in the EDR concept lexicon.
·
New
Mexico State University:
MIKROKOSMOS approx. 4,000 terms, general coverage, detailed, taxonomized
for Natural Language applications.
·
European Union: EuroWordNetóunder construction;
probably approx. 50,000 terms, little detail, taxonomized on Naive Semantics /
Cognitive Science principles.
·
LXT Inc.: UMLS medical ontology exceeds 50,000
terms, medium detail, taxonomized for medical reasoning applications.
Perhaps some of these should also be
on our list if they have "matured".
A last point/issue concerns
alignment between our starting sources and how to start on this. Martin Doerr
and others did some work reported in "Towards a Core Ontology for
Information Integration" and described
the comparison and convergence of 2 ontologies using the OntoClean approach.
(Guarino, N. and Welty, C., "Evaluating ontological decisions with
OntoClean," Communiations of the ACM,
45 (2), pp. 61-65, 2002,)
This uses an analyses of top-level
ontological distinctions related to:
1. instantiation versus membership
2. part-of and mereological axioms
3. extensionality
4. connection
5. location and extension
6. co-extension, co-connection
7. unity, singularity and plurality
8. dependence/independence
The claim is that the OntoClean
approach "enables: the detection of concept definitions that are lacking
in clarity or rigidity; the justification of valid sub-sumption relations; and
the detection of invalid sub-sumption declarations. "
Would it be useful to start looking
at the matchup of some of our "seed" ontologies in this way (or a
better way that might be proposed)? The Doerr paper discusses the process of
finding common conceptualizations by equivalency between a concept of
"Temporality" on Ont1 and "Temporal Entity" in Ont2 or
"Action" and "Activity" etc. Some of the foundation
concepts. It might be useful to make our discussions concrete if we are
planning on using a merger of UMLS
DOLCE/BFO, SUMO, OpenCyc, ISO
15926 etc.
Regards,
|
_________________________________________________________________
Message Archives: http://colab.cim3.net/forum/ontac-forum/
To Post: mailto:ontac-forum@xxxxxxxxxxxxxx
Subscribe/Unsubscribe/Config:
http://colab.cim3.net/mailman/listinfo/ontac-forum/
Shared Files: http://colab.cim3.net/file/work/SICoP/ontac/
Community Wiki:
http://colab.cim3.net/cgi-bin/wiki.pl?SICoP/OntologyTaxonomyCoordinatingWG (01)
|