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From: "Sergio Navega" <>
Subject: Re: Rickert, Balter, lookup tables and intelligence
Date: 17 Feb 1999 00:00:00 GMT
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Aaron Sloman See text for reply address wrote in message
>But there are deeper objections to the HLUT, some mentioned below.
>> The hypothetical HLUT is such that all learning that could possibly be
>> done within a finite lifetime in all the environments that anyone could
>> describe within a finite lifetime with one finite alphabet  is already
>> represented as state transitions within the HLUT.
>Rickert probably assumes that no finite alphabet could suffice to
>characterise human experience and learning. But sufficiently close
>approximations may be achievable. Compare the use of fixed precision
>floating point numbers to represent real numbers in computers. If you
>take enough care you can simulate continuous processes using them, and
>this is done every day in scientific and engineering laboratories.
>Of course, as Balter acknowledges later, even using a small finite
>alphabet, no machine with a large enough HLUT to pass the kinds of tests
>envisaged could possibly be built, because a machine with a table that
>anticipated *all* the possible external (discretised) contexts that
>could occur in a human life time along with *all* the appropriate
>responses, would require a larger memory than could fit into the
>physical universe.

Prof. Sloman, I mostly concur with your insightful comments. I would
like to add two observations related with the impossibility of HLUTs.

a) It is clear that, if it were possible, a HLUT storing all possible
action/reaction pairs of multisensory streams as they appear in humans
would be incommensurably large. If we think like mathematicians for
a while, nothing would prevent us from using all the matter in the
universe to represent the information in that table. That's the
problem: we would have to use matter from Andromeda, 2 million
light-years from Earth. We must keep Albert Einstein's theories
working here. Then, the time to recover our balance from a sneeze
would have to be measured in hundreds or thousands of years, just
to access the proper entries in the table and transport it to
the "fake" robot. This would hardly be accepted as human behavior.

b) This second reason is not exactly an impediment for HLUT, but is
a terrible complication factor (as if the size were not enough...).
We know that there's a lot of "noise" in some firings of neurons.
William Calvin wrote a paper in 1967 about this. I have an impression
that this noise does not only happen in motor-related neurons
(our hands, fingers and arms are not completely stable), but I
think this also happens on the more "noble" parts of our brain. The
end result (this is just an hypothesis), is that this may be a
driving force behind most of our "novel" an creative thoughts.
Being driven occasionally by "wild images" is one of the sensible
explanations for the surge of creative discoveries of several
scientists in the past. Most of these wanderings conduct to
nothing useful at all. But in the middle of those useless,
that magic idea emerges. A HLUT would not be able to present such
a "usefully" randomic behavior, because any noise introduced in
its entries would disrupt very fast its integrity.

Sergio Navega.

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