Kathy, John B., Chris M., and Adam, (01)
First I'd like to correct a misunderstanding: (02)
JFS>> ...It has been *proved* that physics as a whole
>> does not have a consistent foundation. (03)
KBL> Not true. Physics is *incomplete* but not inconsistent. (04)
What I said was that the well-established theories of physics
are individually consistent, but the conjunction of all of them
is inconsistent. (05)
KBL> As for inconsistencies, one has to attempt to put everything
> into a single formalism even to attempt to find inconsistencies. (06)
Indeed, that is an excellent research project. Scientists in
all fields have been engaged in that project for many centuries
and will continue to be so engaged for many centuries to come. (07)
Second, I strongly endorse John B's point: (08)
JB> All of that groundwork requires richer notions of structure
> and modularities in ontologies than is commonly found in
> current offerings.
>
> My own take on this (but it will be an empirical matter) is
> that we won't *need* 'a common basis' when we get this right. (09)
Third, I believe that approaches along the lines that John B.
recommends help reinforce skepticism along the following lines: (010)
CM> I am simply skeptical of two things: (1) Whether there is
> any coherent sense in which such an on ontology could ever
> function as any sort of "medium" for supporting general
> interoperability (which is what the person from NASA seemed
> to be advocating) and (2) even if the answer to (1) is "yes",
> I am skeptical of whether such an approach would have any
> advantage over a straightforward "federated" approach on
> which distinct ontologies are integrated in a more piecemeal
> fashion; I am, that is, skeptical of the extent to which an
> upper ontology is needed to *support* interoperability. (011)
I have nothing against "hope-based initiatives" for developing
global ontologies as research projects. But there is zero
evidence that those hopes, even if realized, would magically
solve any of the very serious problems of interoperability. (012)
Among those problems, the most overwhelmingly important is
to integrate the trillions of dollars of *legacy software*
into the future. For the next 40 years, that software will
be the dominant base with which all new systems must be
interoperable. (013)
AP> I'm sympathetic to using SUMO for semantic interoperability.
> When I've done projects in that area, it has worked well. At
> the risk of stating the obvious, the advantage, at least in
> theory, of a common model over a federated approach is that
> one has mappings linear in the number of products needing
> integration, rather than potentially N2. (014)
That is fine for projects that are being started from scratch.
But as I just said, the millions of incompatible legacy systems
are not going away. A methodology for supporting federated
systems is essential for dealing with current software. (015)
Furthermore, *even if* some ideal common ontology should
magically appear tomorrow, we would still need federated tools
to support different microtheories that are based on the common
upper levels. (016)
Finally, I recommend the following article by Alan Bundy and
colleagues, which helps explain some of the theoretical
underpinnings of the problems we have been discussing. (017)
John
____________________________________________________________ (018)
Source: http://www.inf.ed.ac.uk/publications/online/0837.pdf (019)
On Repairing Reasoning Reversals via Representational Refinements (020)
Alan Bundy, Fiona McNeill and Chris Walton (021)
Excerpt: (022)
The first author [AB] has a vivid memory of his introductory
applied mathematics lecture during his first year at university.
The lecturer delivered a sermon designed to rid the incoming
students of a heresy. This heresy was to entertain a vision
of a complete mathematical model of the world. The lecturer
correctly prophesied that the students were dissatisfied with
the patent inadequacies of the mathematical models they had
learnt at school and impatient, now they had arrived in the
adult university world, to learn about sophisticated models
that were free of caveats such as treating the weight of the
string as negligible or ignoring the friction of the pulley. (023)
They were to be disappointed. Complete mathematical models
of the real world were unattainable, because it was infinitely
rich. Deciding which elements of the world were to be modelled
and which could be safely ignored was the very essence of
applied mathematics. It was a skill that students had to learn,
not one that they could render redundant by modelling everything. (024)
This all now seems obvious. AB is surprised at the naivety
of his younger self -- since, before the sermon, he certainly
was guilty of this very heresy. But it seems this lesson needs
to be constantly relearnt by the AI community. We too model
the real world, for instance, with symbolic representations
of common-sense knowledge. We too become impatient with the
inadequacies of our models and strive to enrich them. We too
dream of a complete model of common-sense knowledge and even
aim to implement such a model, cf. the Cyc Project1. But even
Cycorp is learning to cure itself of this heresy, by tailoring
particular knowledge bases to particular applications,
underpinned by a common core. (025)
If we accept the need to free ourselves of this heresy and
accept that knowledge bases only need to be good enough
for their application, then there is a corollary that we must
also accept: the need for the knowledge in them to be fluent,
i.e., to change during its use. And, of course, we do accept
this corollary. We build adaptive systems that learn to tailor
their behaviour to a user or improve their capabilities over
time. We have belief-revision mechanisms, such as truth
maintenance (Doyle 1979), that add and remove knowledge
from the knowledge base. (026)
However, it is the thesis of this paper that none of this goes
far enough. In addition, we must consider the dynamic evolution
of the underlying formalism in which the knowledge is represented.
To be concrete, in a logic-based representation the predicates
and functions, their arities and their types, may all need to
change during the course of reasoning... (027)
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