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AIList Digest Volume 2 Issue 020
AIList Digest Friday, 17 Feb 1984 Volume 2 : Issue 20
Today's Topics:
Lisp - Timing Data Caveat,
Bindings - G. Spencer Brown,
Logic - Nature of Undecidability,
Brain Theory - Parallelism,
Expert Systems - Need for Perception,
AI Culture - Work in Progress,
Seminars - Learning & Automatic Deduction & Commonsense Reasoning
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Date: 16 Feb 1984 1417-PST
From: VANBUER at USC-ECL.ARPA
Subject: Timing Data Caveat
A warning on the TAK performance testing: this code only exercises
function calling and small integer arithmetic, and none of things
most heavily used in "real" lisp programming: CONSing, garbage collection,
paging (ai stuff is big after all).
Darrel J. Van Buer
------------------------------
Date: Wed, 15 Feb 84 11:15:21 EST
From: John McLean <mclean@NRL-CSS>
Subject: G. Spencer-Brown and undecidable propositions
G. Spencer-Brown is very much alive. He spent several months at NRL a couple
of years ago and presented lectures on his purported proof of the four color
theorem. Having heard him lecture on several topics previously, I did not feel
motivated to attend his lectures on the four color theorem so I can't comment
on them first hand. Those who knew him better than I believe that he is
currently at Oxford or Cambridge. By the way, he was not a friend of Russell's
as far as I know. Russell merely said something somewhat positive about LAWS
OF FORM.
With respect to undecidability, I can't figure out what Charlie Crummer means
by "undecidable proposition". The definition I have always seen is that a
proposition is undecidable with respect to a set of axioms if it is
independent, i.e,. neither the proposition nor its negation is provable.
(An undecidable theory is a different kettle of fish altogether.) Examples are
Euclid's 5th postulate with respect to the other 4, Goedel's sentence with
respect to first order number theory, the continuum hypothesis with respect to
set theory, etc. I can't figure out the claim that one can't decide whether
an undecidable proposition is decidable or not. Euclid's 5th postulate,
Goedel's sentence, and the continuum hypothesis have been proven to be
undecidable. For simple theories, such as sentential logic (i.e., no
quantifiers), there are even algorithms for detecting undecidability.
John McLean
------------------------------
Date: Wed, 15 Feb 84 11:18:43 PST
From: Charlie Crummer <crummer@AEROSPACE>
Subject: G. Spencer-Brown and undecidable propositions
Thanks for the lead to G. S-B. I think I understand what he is driving at with
THE LAWS OF FORM so I would like to see his alledged 4-color proof.
Re: undecidability... Is it true that all propositions can be proved decidable
or not with respect to a particular axiomatic system from WITHIN that system?
My understanding is that this is not generally possible. Example (Not a proof
of my understanding): Is the value of the statement "This statement is false."
decidable from within Boolean logic? It seems to me that from within Boolean
logic, i.e. 2-valued logic, all that would be seen is that no matter how long
I crank I never seem to be able to settle down to a unique value. If this
proposition is fed to a 2-valued logic program (written in PROLOG, LISP, or
whatever language one desires) the program just won't halt. From OUTSIDE the
machine, a human programmer can easily detect the problem but from WITHIN
the Boolean system it's not possible. This seems to be an example of the
halting problem.
--Charlie
------------------------------
Date: 16 Feb 1984 12:22 EST (Thu)
From: "Steven C. Bagley" <BAGLEY%MIT-OZ@MIT-MC.ARPA>
Subject: Quite more than you want to know about George Spencer Brown
Yes, Spencer Brown was associated with Russell, but since Lord Russell
died recently (1970), I think it safe to assume that not ALL of his
associates are dead, yet, at least.
There was a brief piece about Spencer Brown in "New Scientist" several
years ago (vol. 73, no. 1033, January 6, 1977, page 6). Here are two
interesting quotes:
"What sets him apart from the many others who have claimed a proof of
the [four-color] theorem are his technique, and his personal style.
Spencer Brown's technique rests on a book he wrote in 1964 called
`Laws of Form.' George Allen and Unwin published it in 1969, on the
recommendation of Bertrand Russell. In the book he develops a new
algebra of logic -- from which the normal Boolean algebra (a means of
representing propositions and arguments with symbols) can be derived.
The book has had a mixed reputation, from `a work of genius' to
`pretentious triviality.' It is certainly unorthodox, and mixes
metaphysics and mathematics. Russell himself was taken with the work,
and mentions it in his autobiography....
The style of the man is extravagant -- he stays at the Savoy -- and
all-embracing. He was in the Royal Navy in the Second World War; has
degrees in philosophy and psychology (but not mathematics); was a
lecturer in logic at Christ Church College, Oxford; wrote a treatise
on probability; a volume of poetry, and a novel; was a chief logic
designer with Mullard Equipment Ltd where his patented design of a
transistorised elevator logic circuit led to `Laws of Form'; has two
world records for gliding; and presently lectures part-time in the
mathematics department at the University of Cambridge while also
managing his publishing business."
I know of two reviews of "Laws of Form": one by Stafford Beer, the
British cyberneticist, which appeared in "Nature," vol. 223, Sept 27,
1969, and the other by Lancelot Law Whyte, which was published in the
British Journal of the Philosophy of Science, vol 23, 1972, pages
291-292.
Spencer Brown's probability work was published in a book called
"Probability and Scientific Inference", in the late 1950's, if my
memory serves me correctly. There is also an early article in
"Nature" called "Statistical Significance in Psychical Research", vol.
172, July 25, 1953, pp. 154-156. A comment by Soal, Stratton, and
Trouless on this article appeared in "Nature" vol 172, Sept 26, 1953,
page 594, and a reply by Spencer Brown immediately follows. The first
sentence of the initial article reads as follows: "It is proposed to
show that the logical form of the data derived from experiments in
psychical research which depend upon statistical tests is such as to
provide little evidence for telepathy, clairvoyance, precognition,
psychokinesis, etc., but to give some grounds for questioning the
practical validity of the test of significance used." Careful Spencer
Brown watchers will be interested to note that this article lists his
affliation as the Department of Zoology and Comparative Anatomy,
Oxford; he really gets around.
His works have had a rather widespread, if unorthodox, impact.
Spencer Brown and "Laws of Form" are mentioned in Adam Smith's Powers
of Mind, a survey of techniques for mind expansion, contraction,
adjustment, etc., e.g., EST, various flavors of hallucinogens, are
briefly noted in Aurthur Koestler's The Roots of Coincidence, which
is, quite naturally enough, about probability, coincidence, and
synchronicity, and are mentioned, again, in "The Dyadic Cyclone," by
Dr. John C. Lilly, dolphin aficionado, and consciousness expander,
extraordinaire.
If this isn't an eclectic enough collection of trivia about Spencer
Brown, keep reading. Here is quote from his book "Only Two Can Play
This Game", written under the pseudonym of James Keys. "To put it
bluntly, it looks as if the male is so afraid of the fundamentally
different order of being of the female, so terrified of her huge
magical feminine power of destruction and regeneration, that he
doesn't look at her as she really is, he is afraid to accept the
difference, and so has repressed into his unconscious the whole idea
of her as ANOTHER ORDER OF BEING, from whom he might learn what he
could not know of himself alone, and replaced her with the idea of a
sort of second-class replica of himself who, because she plays the
part of a man so much worse than a man, he can feel safe with because
he can despise her."
There are some notes at the end of this book (which isn't really a
novel, but his reflections, written in the heat of the moment, about
the breakup a love affair) which resemble parts of "Laws of Form":
"Space is a construct. In reality there is no space. Time is also a
construct. In reality there is no time. In eternity there is space
but no time. In the deepest order of eternity there is no space....In
a qualityless order, to make any distinction at all is at once to
construct all things in embryo...."
And last, I have no idea of his present-day whereabouts. Perhaps try
writing to him c/o Cambridge University.
------------------------------
Date: Thu, 16 Feb 84 13:58:28 PST
From: Charlie Crummer <crummer@AEROSPACE>
Subject: Quite more than you want to know about George Spencer Brown
Thank you for the copious information on G. S-B. If I can't get in touch
with him now, it will be because he does not want to be found.
After the first reading of the first page of "The Laws of Form" I almost
threw the book away. I am glad, however, that I didn't. I have read it
several times and thought carefully about it and I think that there is much
substance to it.
--Charlie
------------------------------
Date: 15 Feb 84 2302 PST
From: John McCarthy <JMC@SU-AI>
Subject: Serial or parallel
It seems to me that introspection can tell us that the brain
does many things serially. For example, a student with 5 problems
on an examination cannot set 5 processes working on them. Indeed
I can't see that introspection indicates that anything is done
in parallel, although it does indicate that many things are done
subconsciously. This is non-trivial, because one could imagine
a mind that could set several processes going subconsciously and
then look at them from time to time to see what progress they
were making.
On the other hand, anatomy suggests and physiological
experiments confirm that the brain does many things in parallel.
These things include low level vision processing and probably
also low level auditory processing and also reflexes. For example,
the blink reflex seems to proceed without thought, although it
can be observed and in parallel with whatever else is going on.
Indeed one might regard the blink reflex and some well learned
habits as counter-examples to my assertion that one can't set
parallel processes going and then observe them.
All else seems to be conjecture. I'll conjecture that
a division of neural activity into serial and parallel activities
developed very early in evolution. For example, a bee's eye is
a parallel device, but the bee carries out long chains of serial
activities in foraging. My more adventurous conjecture is that
primate level intelligence involves applying parallel pattern
recognition processes evolve in connection with vision to records
of the serial activities of the organism. The parallel processes
of recognition are themselves subconscious, but the results have
to take part in the serial activity. Finally, seriality seems
to be required for coherence. An animal that seeks food by
locomotion works properly only if it can go in one direction
at a time, whereas a sea anemone can wave all its tentacles at
once and needs only very primitive seriality that can spread
in a wave of activity.
Perhaps someone who knows more physiology can offer more
information about the division of animal activity into serial
and parallel kinds.
------------------------------
Date: Wed, 15 Feb 84 22:40:48 pst
From: finnca1%ucbtopaz.CC@Berkeley
Subject: Re: "You cant go home again"
Date: Sun, 12 Feb 84 14:18:04 EST
From: Brint <abc@brl-bmd>
I couldn't agree more (with your feelings of regret at not
capturing the expertise of the "oldster" in meterological
lore).
My dad was one of the best automotive diagnosticians in
Baltimore [...]
Ah yes, the scarcest of experts these days: a truly competent auto
mechanic! But don't you still need an expert to PERCEIVE the subtle
auditory cues and translate them into symbolic form?
Living in the world is a full time job, it seems.
Dave N. (...ucbvax!ucbtopaz!finnca1)
------------------------------
Date: Monday, 13 Feb 1984 18:37:35-PST
From: decwrl!rhea!glivet!zurko@Shasta
Subject: Re: The "world" of CS
[Forwarded from the Human-Nets digest by Laws@SRI-AI.]
The best place for you to start would be with Sheri Turkle, a
professor at MIT's STS department. She's been studying both the
official and unofficial members of the computer science world as a
culture/society for a few years now. In fact, she's supposed to be
putting a book out on her findings, "The Intimate Machine". Anyone
heard what's up with it? I thought it was supposed to be out last
Sept, but I haven't been able to find it.
Mez
------------------------------
Date: 14 Feb 84 21:50:52 EST
From: Michael Sims <MSIMS@RUTGERS.ARPA>
Subject: Learning Seminar
[Forwarded from the Rutgers bboard by Laws@SRI-AI.]
MACHINE LEARNING BROWN BAG SEMINAR
Title: When to Learn
Speaker: Michael Sims
Date: Wednesday, Feb. 15, 1984 - 12:00-1:30
Location: Hill Center, Room 254 (note new location)
In this informal talk I will describe issues which I have broadly
labeled 'when to learn'. Most AI learning investigations have
concentrated on the mechanisms of learning. In part this is a
reasonable consequence of AI's close relationship with the 'general
process tradition' of psychology [1]. The influences of ecological and
ethological (i.e., animal behavior) investigations have recently
challenged this research methodology in psychology, and I believe this
has important ramifications for investigations of machine learning. In
particular, this influence would suggest that learning is something
which takes place when an appropriate environment and an appropriate
learning mechanism are present, and that it is inappropriate to
describe learning by describing a learning mechanism without describing
the environment in which it operates. The most cogent new issues which
arise are the description of the environment, and the confronting of
the issue of 'when to learn in a rich environment'. By a learning
system in a 'rich environment' I mean a learning system which must
extract the items to be learned from sensory input which is too rich to
be exhaustively stored. Most present learning systems operate in such
a restrictive environment that there is no question of what or when to
learn. I will also present a general architecture for such a learning
system in a rich environment, called a Pattern Directed Learning Model,
which was motivated by biological learning systems.
References
[1] Johnston, T. D.
Contrasting approaches to a theory of learning.
Behavioral and Brain Sciences 4:125-173, 1981.
------------------------------
Date: Wed 15 Feb 84 13:16:07-PST
From: Richard Treitel <TREITEL@SUMEX-AIM.ARPA>
Subject: "Automatic deduction" and other stuff
[Forwarded from the Stanford bboard by Laws@SRI-AI.]
A reminder that the seminar on automatic reasoning / theorem proving /logic
programming / mumble mumble mumble which I advertised earlier is going to
begin shortly, under one title or another. It will tentatively be on
Wednesdays at 1:30 in MJH301. If you wish to be on the mailing list for this,
please mail to me or Yoni Malachi (YM@SAIL). But if you are already on
Carolyn Talcott's mailing list for the MTC seminars, you will probably be
included on the new list unless you ask not to be.
For those interested specifically in the MRS system, we plan to continue MRS
meetings, also on Weds., at 10:30, starting shortly. I expect to announce
such meetings on the MRSusers distribution list. To get on this, mail to me
or Milt Grinberg (GRINBERG@SUMEX). Note that MRSusers will contain other
announcements related to MRS as well.
- Richard
------------------------------
Date: Wed 15 Feb 84
Subject: McCarthy Lectures on Commonsense Knowledge
[Forwarded from the Stanford CSLI newsletter by Laws@SRI.]
MCCARTHY LECTURES ON THE FORMALIZATION OF COMMONSENSE KNOWLEDGE
John McCarthy will present the remaining three lectures of his
series (the first of the four was held January 20) at 3:00 p.m. in the
Ventura Hall Seminar Room on the dates shown below.
Friday, Feb. 17 "The Circumscription Mode of Nonmonotonic Reasoning"
Applications of circumscription to formalizing commonsense
facts. Application to the frame problem, the qualification
problem, and to the STRIPS assumption.
Friday, March 2 "Formalization of Knowledge and Belief"
Modal and first-order formalisms. Formalisms in which possible
worlds are explicit objects. Concepts and propositions as
objects in theories.
Friday, March 9 "Philosophical Conclusions Arising from AI Work"
Approximate theories, second-order definitions of concepts,
ascription of mental qualities to machines.
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End of AIList Digest
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