Re: SUO: Re: Ballot Comment - 3D versus 4D.
Graham,
I agree with your comments, and I'd to make some further observations:
> GH> I guess this approaches the heart of the distinction with my own
> perspective. I believe the developers should be making a flexible structure
> that accommodates both perspectives, and works with the appropriate one for
> the circumstances in question at any particular instance.
> GH> The underlying difference with this approach is that most of the
> ontology development seems to want to concentrate on a single conceptual
> dimension, meaning that the perspective on any particular item is to be
> rigidly fixed (eg. We may decide to always treat cars as 3D, but people as
> 4D). I don't think this will ever achieve the universality we want. That's
> why I am calling for a more complicated approach that has "depth", and
> accommodates more precisely to the conceptual circumstances and requirements
> of any particular task.
I endorse Graham's view of the requirements:
1. The first key phrase in Graham's note is "a flexible structure
that accommodates both perspectives, and works with the appropriate
one for the circumstances in question at any particular instance."
My only recommendation is to replace the word "both" with "all".
2. I agree with Graham's complaint that the SUMO developers "want to
concentrate on a single conceptual dimension, meaning that the
perspective on any particular item is to be rigidly fixed."
A single rigid perspective on anything is unrealistic. It cannot
accommodate existing systems, which have been developed from many
different perspectives, and it can never accommodate any future
view that differs from what the SUMO developers intended. Only
God could have the omniscience to make such an approach work, and
He wisely gave us a choice.
3. I wholeheartedly endorse Graham's conclusion: "I am calling for
a more complicated approach that has "depth", and accommodates more
precisely to the conceptual circumstances and requirements of any
particular task.
My only suggestion is to replace the word "complicated" with
"flexible". For the reasons discussed below, I believe that
the current SUMO approach is vastly more complicated than any
modular approach could ever be.
Following is an excerpt from a paper by E. W. Dijkstra, entitled
"On our inability to do much." He was writing about the need to
break programs into smaller, more manageable modules, but his
comments apply equally well (if not more so) to ontology. I found
this excerpt at the web site, which discusses several other
contributors on the same theme, including Herb Simon, Fred Brooks,
Tony Hoare, and others. Following is the reference:
http://www.scenarioplus.org.uk/handwritten/historical/historical_text.htm
After the excerpt by Dijkstra, I also quote Simon's example about the
two watchmakers. The monolithic SUMO approach is doomed for exactly
the same reasons as the monolithic watchmaker.
John Sowa
_______________________________________________________________________
From _Notes on Structured Programming_ by E.W.Dijkstra:
ON OUR INABILITY TO DO MUCH
I am faced with a basic problem of presentation. What I am really
concerned about is the composition of large programs, the text of which
may be, say, of the same size as the whole text of this chapter. Also
I have to include examples to illustrate the various techniques. For
practical reasons, the demonstration programs must be small, many times
smaller than the "life-size programs" I have in mind. My basic problem
is that precisely this difference in scale is one of the major sources
of our difficulties in programming!
It would be very nice if I could illustrate the various techniques with
small demonstration programs and could conclude with "..and when faced
with a program a thousand times as large, you compose it in the same
way." This common educational device, however, would be self-defeating
as one of my central themes will be that any two things that differ
in some respect by a factor of already a hundred or more, are utterly
incomparable. History has shown that this truth is very hard to
believe. Apparently we are too much trained to disregard differences
in scale, to treat them as "gradual differences that are not essential".
We tell ourselves that what we can do once, we can also do twice and by
induction we fool ourselves into believing that we can do it as many
times as needed, but this is just not true! A factor of a thousand is
already far beyond our powers of imagination!
Let me give you [an] example to rub this in. A one-year old child will
crawl on all fours with a speed of, say, one mile per hour. But a speed
of a thousand miles per hour is that of a supersonic jet. Considered as
objects with moving ability the child and the jet are incomparable, for
whatever one can do the other cannot and vice versa.
To complicate matters still further, problems of size do not only cause
me problems of presentation, but they lie at the heart of the subject:
widespread underestimation of the specific difficulties of size seems
one of the major underlying causes of the current software failure. to
all this I can see only one answer, viz. to treat problems of size as
explicitly as possible...
To start with, we have the "size" of the computation, i.e. the amount
of information and the number of operations involved in it. It is
essential that this size is large, for if it were really small, it would
be easier not to use the computer at all and to do it by hand. The
automatic computer owes its right to exist, its usefulness, precisely to
its ability to perform large computations where we humans cannot. We
want the computer to do what we could never do ourselves and the power
of present-day machinery is such that even small computations are by
their very size already far beyond the powers of our unaided
imagination.
________________________________________________________________________
The Evolution of Complex Systems,
From Herbert A. Simon, "The Architecture of Complexity: Hierarchic
Systems," _Proceedings of the American Philosophical Society_, 106,
Dec 1962, 467-482.
Let me introduce the topic of evolution with a parable. There once
were two watchmakers, named Hora and Tempus, who manufactured very fine
watches. Both of them were highly regarded, and the phones in their
workshops rang frequently - new customers were constantly calling them.
However, Hora prospered, while Tempus became poorer and poorer and
finally lost his shop. What was the reason?
The watches the men made consisted of about 1,000 parts each. Tempus
had so constructed his that if he had one partly assembled and had to
put it down - to answer the phone, say - it immediately fell to pieces
and had to be reassembled from the elements. The better the customers
liked his watches, the more they phoned him and the more difficult it
became for him to find enough uninterrupted time to finish a watch.
The watches that Hora made were no less complex than those of Tempus.
But he had designed them so that he could put together subassemblies of
about ten elements each. Ten of these subassemblies, again, could be
put together into a larger subassembly; and a system of ten of the
latter subassemblies constituted the whole watch. Hence, when Hora had
to put down a partly assembled watch to answer the phone, he lost only a
small part of his work, and he assembled his watches in only a fraction
of the man-hours it took Tempus'.
It is rather easy to make a quantitative analysis of the relative
difficulty of the tasks of Tempus and Hora: suppose the probability
that an interruption will occur, while a part is being added to an
incomplete assembly, is p. Then the probability that Tempus can complete
a watch he has started without interruption is (1 - p)1000 - a very
small number unless p is 0.001 or less. Each interruption will cost
on the average the time to assemble 111 parts (the expected number
assembled before interruption). On the other hand, Hora has to complete
111 subassemblies of ten parts each. The probability that he will not
be interrupted while completing any one of these is (1 - p)10, and each
interruption will cost only about the time required to assemble five
parts.
Now if p is about 0.01 - that is, there is one chance in a hundred that
either watchmaker will be interrupted while adding any one part to an
assembly - then a straightforward calculation shows that it will take
Tempus on the average about four thousand times as long to assemble a
watch as Hora.