P.S.: Of course, this whole issue is also very much what Matthias Samwald seeks to address in the biO zen ontology framework as well (http://neuroscientific.net/index.php?id=43)

On Jul 8, 2006, at 12:55 AM, William Bug wrote:

Hi All,

I think after following these discussions over the last few weeks about use of ontologies and bridging of ontologies on SW projects, I have to say, I believe the "impedance mismatch" on what different folks mean by ontology and the practical use for ontological resources is way to great to address via email.  As I've said in several neuroinformatics ontology meetings, we really need to start off by agreeing on an ontological framework for the concept ontology.

I'm loathe to say this, but maybe this whole issue should be tabled for an F2F meeting.

I really wouldn't want this issue to hold up the real work the HCLSIG has already begun to make useful progress on.  My only fear is these fundamental differences may in fact be incommensurable.

As to the issues Xiaoshu refers here, I think "factoring out" and "modularizing" are two very distinct issues here.

The "factoring out" Trish refers to has a very specific meaning in the current practice of ontology development embodied in the OBO Foundry principles.  It relates to the search for ontological "universals" that can be used to create a subsumption 'is_a' hierarchy.  This approach to formal KR has been very effective both in formal ontological philosophical domains, as well as in AI (see Rodney Brooks' Subsumption Architecture) and computational linguistics.  In the particular case of the foundational ontology being used here (BFO), a continuant (or endurant as labeled in other formalisms) means "entities in the world that endure through time: entities which persist self-identically even while undergoing changes of various sorts" (please see section "1.3 Continuants and Occurrents" in "Biodynamic Ontology" [http://ontology.buffalo.edu/medo/biodynamic.pdf]).  Similar core entities are defined for other foundational ontologies, though the ontological commitments incurred by using a specific foundational ontology can be quite different (e.g., BFO vs. DOLCE).

To use the example you have chosen, for an anatomist to want to use FuGO and be ontological compatible, they need only use an ontology founded on the same definition of continuants & occurents.  How does this differ from what I think you are claiming.  An anatomist need not necessarily care about the details of FuGO entities bearing no relation to data they intend to semantically integrate with (such as 'LC_instrument') to remain fundamentally compatible with FuGO.  They only need agree on the definition and use of the foundational levels of the ontology they share in common - in this case 'Continuant', 'Independent_ continuant', and 'Object'.  In fact, this would be encouraged by the OBO Foundry participants - use FuGO for formal semantic descriptions of assay/instrument/reagent provenance and use the Foundational Model of Anatomy to deal with anatomy (right now, just human anatomy, but that is being worked on) - both of which are founded on BFO.

The "modularization" you refer to via namespaces relates to a conceptually different issue, as I see it.  Even though the use of namespace - especially in XML & RDF - has advanced to something considerably beyond its original application of simply avoiding tag/term/name "collisions", the "modularization" namespaces can support in XML space is distinctly different from the "factoring out" of universals to which Trish referred.

Using the namespace facility inherent in XML formalisms might be a useful way of enabling people to exchange different world views for sub-regions of the graph, that's true.  But it is by no means a requirement.  One should still expect whether or not you are using namespaces to chop up or modularize different portions of the ontological graph, you are still following the same principle of extrapolating to universals, even if the universals for "namespace_a"'s coverage of the cardinal parts of a liquid chromatographic apparatus differed from the universals defined for "namespace_b"s coverage of the cardinal parts of a liquid chromatographic apparatus .

If namespaces were used as the primary means of "factoring out" universals, you could end up with quite a proliferation of namespaces for FuGO - in the extreme - one for every node in the graph.

It may be of some use to separate the different ontological sources using namespaces.   For instance, there may be some utility to specifying the BFO elements in their own namespace, so as to clearly separate those entities created by the FuGO group, and those derived directly from BFO.  In the end, however, the ontology construction performed by the FuGO group is very much wedded via subsumption to the many ontological commitments made in BFO, so it's not clear to me there would be anything to gain from doing this, apart from making the layers separable for curatorial purposes.  For instance, if FuGO v1.0 is build off BFO v1.0, having them in separate namespaces may be useful should a new new v1.1 of BFO be released.  Migrating FuGO v1.0 to use BFO v1.1 could be easier to do, if they were namespace distinct, but, of course, in doing so, the altered nature of the ontological contract would require you to bump the version of FuGO once you've done this AND probably perform quite a bit of manual review to determine whether the FuGO graph is still valid when linked to v1.1 of BFO.

This is an issue we've begun to examine on the BIRN Ontology Task Force.  The BIRNLex knowledge resource we are constructing has an even more complex relation to a variety of external community ontologies, including BFO, FuGO, FMA, PaTO, etc.

My sense of what you are trying to do with O3 is to separate the intensional conceptualzation from the lexicon used to extend this view of the world into a specific application space - for instance, providing a URI for the concepts in the ConcreteOntology.  I am a strong proponent of separating the lexicon from the ontological graph.  Having said that, most of the OBO Foundry ontologies are using terms to label the nodes in the graph just to make them more human readable.  At least where the basic "factoring out" process is concerned, the goal is not to swayed by the lexicon when constructing the ontological graph, and in that sense, they are already separating the extensional view of the semantic network from the intentional conceptualization.

As to the issue of ComplexOntology vs. LocalOntology as you describe it, I think this is very much at odds with the OBO Foundry approach.  All OBO Foundry ontologies are ComplexOntologies in that they are all being adjusted to build off the BFO.  Even more troublesome is the fact these foundational biomedical ontologies are MEANT to be used to create more complex ontologies and DL frameworks through coordination via the OBO Relation Ontology.  That would make all ontological development being encouraged by the OBO group break the model you are recommending for maximal ontology re-use and ease of knowledge map integration.

It's also possible O3 is more commensurate with DOLCE than BFO, in which case, I suppose mapping what you describe here to the OBO Foundry principles would require much more thought (and may, in fact, not be possible).

I wish I could understand what you describe at http://www.charlestoncore.org/ont/2005/08/o3.htm a little better.  I found your Nature Biotech. paper very clear and extremely helpful in several discussions I've been having on the issue of XML vs. RDF, but I really am having a hard time with your description of O3 on that web page.  Is there a publication where you go into this in more detail?

Cheers,
Bill

On Jul 7, 2006, at 4:02 PM, Xiaoshu Wang wrote:


Trish,

Comments inline.

Based on that work, I'd like to follow Eric N's penchant for 
"strawmen" and propose the following amendments to the Proposed 
Classes to give focus to the discussion:

Project
Study
Hypothesis
...

I honestly think before making the list, we should think about how 
ontology should be modulized and how to develop ontologies 
on various 
granualities. I would suggest to start with an ontology 
that has a very coarse granuality.
And developing more detailed ontologies one step at a time.
This is the idea behind FuGE and to some degree FuGO. The 
development of FuGE is an effort to factor out the re-usable 
bits of modelling an experiment that can be used to describe, 
in particular any functional genomics experiment, but perhaps 
some sections could be extended to other types of 
experiments?. The concepts that AJ has included seem to be 
fine with respect to having something to test the proof of 
concept of the idea and technology for linking/searching the 
data. One thing that may need to be added is something to 
indicate the type of experiment so that searches can be 
limited in some way. The ways to go about typing the kind of 
experiment are many so if needed, that can be left for future 
discussions. Depending on how fine grained this effort goes, 
perhaps there is some benefit in joining this work to what 
has been done, at least with functional genomics experiments, 
to develop data standards and exchange formats as these 
efforts represent the granularity needed by the community.

When I mean "factoring out", I mean by grouping terms under different
namespaces.  I just take a brief overlook on FuGO, just taking the first
look that "LC_instrument" is under the same namespace of "continuant"
already tells me there is no modulization whatsoever.  (Please correct me if
I am wrong).  If I were an anatomist, who will conduct experiment, but never
care about LC_instrument.  But if I want to use FuGO's continuant, I would
have to buy in the concepts of LC_instrument as well.  Now, what about some
physicist, electrical engineer, do each scientific community should they
ever want or forced to accept LC_experiment?

To factor it out, for example, you need to break it at least into two
ontologies. One top generic concepts and one lower domain specific ones.
So, at least, people can share the top one without forced to take the bottom
one.  But the right way in my suggested methodology would be at least be
three.  For the simple case, there needs to be at least three: two
LocalOntologies + one Profile (see my classification of ontologies and what
I mean by ontology normalization at
level ontologies want to realign its relations to another high-level
ontology, a new profile can be created to associate them.  The rational for
the basis of  
ontology normalization is to separate ontologies' dependency so they can
gracefully evolve over time... I will stop here.  Otherwise, I would have to
put out my entire manuscript to make it clear.

FuGO, in its current form, would be unable to handle the evolutionary, let
alone the revolutionary change of its ontological terms.   

Using ontology implies that if you want to use one assertion of an 
ontology, you must agree to all assertions made in the ontology. A 
detailed monolithic ontology is what we should avoid. I 
have thought 
of this problem for quite a while.  The BOSS ontology 
created only has 
a three classes (Study, Protocol and Data) and three pairs 
of inverse 
properties.  (Please trust me, I am not trying to promote the BOSS 
ontology here.) What I have really hoped is that we should 
think how the ontologies will be shared before start building 
the ontology.

The same issue also goes to the overlap between FUGO with 
the proposed 
self-descriptive experiement ontology. In fact, I think all 
biological 
related ontology will perhaps touche on the topic of 
experiment in one 
way or the other.  Hence, if each ontology's designers don't factor 
out their ontology design, the eventual result will be a bunch of 
overlapping monolithic ontologies.

The overlap with the self-descriptive experiment ontology is 
actually with both FuGE and FuGO. FuGE provides a model to 
capture common components of investigations and to provide a 
framework to capture laboratory workflows. FuGO is being 
designed to provide a source of descriptors for the 
annotation of investigations. The scope of FuGO includes the 
design of an investigation, the protocols and instrumentation 
used, the data generated and the types of analysis performed 
on the data. FuGO is not to model any of these particular 
items, but to provide annotation terms as needed by the 
collaborating communities. Of course terms/classes will be 
needed in the ontology to properly fill out the is_a hierachy 
and create needed relationships between classes. Therefore, 
in the FuGE model there will be a reference to use an 
ontology term from some source and in some cases this will be 
FuGO that contains the term. In other cases where an existing 
ontology has already been designed, e.g. Foundational Model 
of Anatomy, a term from this ontology will be used. FuGE 
provides a mechanism to state which ontology the term was 
obtained from so this will be present.

Hiearchy is not modulization.  A tree is a tree, unless its braches can
exist independently.  Whether an ontology is structured or not, btw, which
ontology does not have a structure? has nothing to do with if the ontology
is monolithic or not.

Xiaoshu



Bill Bug
Senior Analyst/Ontological Engineer

Laboratory for Bioimaging  & Anatomical Informatics
www.neuroterrain.org
Department of Neurobiology & Anatomy
Drexel University College of Medicine
2900 Queen Lane
Philadelphia, PA    19129
215 991 8430 (ph)
610 457 0443 (mobile)
215 843 9367 (fax)


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www.neuroterrain.org
Department of Neurobiology & Anatomy
Drexel University College of Medicine
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Philadelphia, PA    19129
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610 457 0443 (mobile)
215 843 9367 (fax)


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