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Discussion on Standard Upper Ontology 2/15/2004 5:27 PM
Comments by Paul Prueitt linked to from [n] designations, n = 1, 2, 3, 4, 5
-----Original Message-----
From: John F. Sowa [mailto:sowa@bestweb.net]
Sent: Sunday, February 15,
2004 3:32 PM
To: portal Cc: Baran,
Robert H.; Ralph Hodgson; BCNGroup Board
Subject: Re: ontology
Paul,
Following is a note that I sent to the SUO Working Group. This note addresses some of the issues related to ontology and the current approaches.
John Sowa
<note begins>
The recent interchange between Azamat Abdoullaev and Danny Ayers raises some important questions about logic and ontology in general and about the Standard Upper Ontology (SUO) and the semantic web in particular. I don't agree 100% with either one, but I agree more with Asha (about 75%) than with Danny (about 25%).
In any case, the questions address important issues about the goals and directions for both the SUO and the semantic web.
I'll start with Danny Ayers' conclusion:
DA
> The bottom line is that the W3C's initiatives
and
> the loftier aims you describe aren't mutually
exclusive.
> I'd go further and suggest that the former
may indeed
> help bootstrap development of the latter.
I agree with the first statement, but disagree with the second. The biggest weakness of the semantic web is illustrated by the popular "layer-cake" diagram
W3C / Semantic Web diagram
As that diagram shows, the W3C started with a purely syntactic foundation consisting of Unicode, the URI naming scheme, and the XML language. There is nothing wrong with including those notations as important parts of the W3C strategy. But what is wrong is the absence of an architecture that addresses the semantic issues. [1]
I agree with Azamat Abdoullaev's statement:
AA
> the administrators running the World Wide Web
Consortium
> rushed the matter by recommending OWL as an
ontology
> language standard fit for structuring the Web
data,
> documents, and applications. Since, beside
the well-known
> merits, the language has bad conceptual
faults which make
> it fall short of wide commercial use.
As an example of the weakness of OWL, I would cite the following claim, which is dangerously and inexcusably [2] misleading:
DA
> As I see it the OWL language attempts to find
the sweet-spot
> between expressive capability and
decidability in the context
> of the web.
From my own little experiments, I'd suggest it
> does quite a good job.
The most serious misconception is the idea that decidability is a property of a language. That is totally misguided. The correct statement is that decidability, like solvability or insolvability, is a property of a problem.
There is an enormous number of problems associated with the WWW, with varying degrees of solvability and with varying requirements for expressive power.
One example of the need for more expressive power than OWL is the query language, of which SQL is the most successful commercial example. The WHERE clause in SQL queries and constraints has the full expressive power of first-order logic, which goes far beyond the capabilities of OWL. Yet all the problems to which SQL queries and constraints are applied can be solved in polynomial time. By any measure of success, SQL certainly hit a "sweet spot", and the failure of OWL to match that sweetness is a serious mistake. [3]
Another serious limitation of OWL is the kludgy syntax which was inherited from RDF, which is a very watered down version of Guha's original proposal, which he only intended as a preliminary step toward a more suitable language. Unfortunately, the absence of published guidelines for the RDF semantics let developers treat the RDF building blocks as a Lego kit that lead to an incoherent florescence of exotic forms that had no common semantics.
Guha and Hayes eventually published a sound semantics, but only after many applications of RDF had been built without any semantics.
AA
> The language is lacking
many significant features of
> relations, both formal
and real. Among real, first of all,
> the relation of cause and
effect is fatally missing.
> Such defects come from
the approach used, purely
> set-theoretical and formal
logical, while any content-based
> (world) ontology
distinguishes internal and external relations,
> avoiding their reduction
to relational properties. 'Being a
> parent' is merely a
relational property, while 'parentage'
> (parenthood, but not the
act or process of parenting) is
> a relation of parent to
child. Or, more generally, the
> relational property of
being a cause is just a monadic
> reduction of causality, the relation of cause to effect.
DA
> Cause and effect can be modelled using OWL -
this is
> something found in OWL-S:
http://www.daml.org/services/owl-s/1.0/owl-s.html
<returning to John Sowa’s comments>
Indeed, a relation named "cause" [4] can be represented in OWL. But there is much more to the concept of causality than just a simple relation. For a brief outline of some of the issues, I suggest a paper I started to write, and which I hope to complete sometime:
Processes and Causality
http://www.jfsowa.com/ontology/causal.htm
DA
> I can't actually see any part of that which
couldn't be
> represented fairly directly using RDF/OWL. As
to the processing
> of the material thus represented, maybe what
you describe falls
> outside of the capability of OWL's
Description Logic - but
> that doesn't mean such logic couldn't be layered on top.
I have no quarrels with using a description logic as a part of a more complete system of logic and ontology. But I strongly disagree with the idea of starting with the bottom layers before any work has been done on the overall architecture. For a view of the kind of design that emerges from that approach, I recommend the following web site:
http://www.winchestermysteryhouse.com/story.html
I agree with Abdoullaev that Aristotle's framework is an outstanding example of the kind of work that is needed for an upper ontology, and I believe that the Aristotelian foundation he recommends should be included in the MSO (Multi-Source Ontology) that is being proposed for the SUO:
However, I also agree with Ayers' cautionary note:
DA
> Whether there is a single universal ontology
is a moot point.
> There's certainly a lot more that can be done
in the field,
> but I would suggest that we can learn a lot from
applying
> what we have already, approaching the problem
from the
> direction of what we do know, rather than that of what we don't.
Where we disagree is whether OWL is a satisfactory example of what we know. The Aristotelian basis of the EIS ontology has been known for over two millennia. FOL (First Order Predicate Logic) has been known for over a century, and the SQL application of FOL has been in commercial use for the past 30 years. Another example is the Horn-clause subset of logic, which has been implemented in many commercial applications for almost as long as SQL.
Although I agree that the possibility of a single universal ontology is "a moot point", there is a lot more that can be done to accommodate multiple ontologies. I have recommended the following paper as an outline of a richer, broader approach, which could be supported by something like the MSO and WebKB:
Signs, Processes, and Language Games
http://www.jfsowa.com/pubs/signproc.htm
John Sowa
Comments by Paul Prueit
[1] Comment on semantics
Here John Sowa and I have different viewpoints, but perhaps a common understanding can be forged. I do not believe that the word “formal” and the word “semantic” ever belongs together. “Formal semantics” as a phase has been used to indicate that meaning can be captured in a formal way. This means that meaning is captured as an abstraction, like first order logic or mathematics. My position is that meaning is experienced by a human as part of mental awareness.
[2] Comment on the inexcusability of this statement
The statement is part a memetic structure that cannot be excused other than to point out that many workers in this area say similar things. The statement is intellectual weak and flatly dishonest.
[3] Comment on mathematical biology and the category error
It is easy to observe that SQL is a wonderful mechanism for addressing data structure within the relational database. No one should take away from this observation. However, many scholars are talking about the limitations of formal mathematics, as in Hilbert mathematics, to model the complex phenomenon that natural science finds when emergence is an essential part of the phenomenon. The limitations of Hilbert mathematics, the ambiguation/disambiguation properties of natural human language, and the formal constructions of computer science all are suggesting something similar.
[4] Comment on the mistaken category error
Robert Rosen extensively worked on the issue of cause. From this work one can suggest that the confusion exhibited by DA is characteristic to the group of fellows who have deeply messed up computer science and the whole field on ontology (machine representation of natural ontology). Calling something “cause” does not make it cause in all of the senses that are needed to model natural ontology and the expression of natural ontology. The problem of causation is similar to the problem of induction. Many in the group of fellows who have messed up our work will treat human cognition as completely reducible to a mechanical and deductive model, and fail to acknowledge that even mathematical induction is not reducible to deduction. So the observations from cognitive neuroscience that mental events are not the same as mathematics inductions is not appreciated at all by these fellows.
http://www.bcngroup.org/area3/pprueitt/kmbook/Chapter4.htm
[5] General comment on Topic Maps standard and the failure in RDF and Cyc type ontology constructions to admit to the need for human in the loop reification of structure and meaning.
I personally deeply value the work that John Sowa has done. My sense is that the goal of representing natural ontology (natural reality and the causation of change) is not going to be achieved by RDF or OWL type ontology, nor by a formal language that is developed to bridge the category gap between how humans think (as insufficiently represented by natural human languages). His work is some of the best work on hard issues. But my sense is that the next layer of innovations will occur by giving up the notion of semantics can be ever formalized.
The pursuit of formal semantics is given up by understanding natural science.
Once this false notion is given up, one does not make errors in the development of software that should be developed to have a tight action perception cycle that brings meaning to sets of signs and symbols.
In this way, we can address the failures of machine aided intelligence gathering and herald in a knowledge age.
http://www.bcngroup.org/python3/fortysix.htm