From: dal3@cbnewsg.cb.att.com (dale.e.parson)
Subject: Re: Questions about SOAR
Organization: AT&T
Distribution: na
Date: Wed, 29 Jul 1992 17:37:46 GMT

In article <CMILLER.92Jul28114711@raven.engin.umich.edu> cmiller@caen.engin.umich.edu writes:
>
>I can give my interpretation of Soar in answering the following answers.  I must caution 
>there can well be other opinions and I'm not necessarily following the "party line"
>with my answers.  Perhaps others in the Soar community will answer differently.
>
>In article <1992Jul27.181203.9316@ils.nwu.edu> pautler@ils.nwu.edu (David Pautler) writes:
>

[some stuff deleted]

>   2) When *don't* humans chunk?  Prof. Newell mentions on the tape that SOAR
>   chunks in some places where humans don't.  There also seems to be a
>   theoretical limit on how much SOAR can declaratively represent its own
>   processing, and thus on what it can chunk on.  Is there empirical
>   evidence showing a definite boundary between content we do chunk on and
>   content we don't?
>
>I don't recall the case where Soar chunks and humans don't.  However, Soar chunks 
>over impasses and since the problem solving determines when impasses will occur,
>the problem solving plays a heavy hand in determining what Soar chunks.  
>
>I don't understand the theoretical limit part of the question.  Given the impasse 
>and its resolution, it is not computationally unreasonable to trace through
>the resolution's dependencies.
>

SOAR chunking certainly isn't parsimonious. It chunks first time,
never eliminates chunks, simply chunks over them if they turn out to
be inappropriate (e.g., because the chunk-forming search episode was
atypical in some way). I prefer automatic behavior acquisition through
practice (loosely, habit formation) a la Schneider & Shiffrin, where
CONSISTENT interaction between intelligent system & environment or
between intelligent system components leads to automatic response
formation. Establishing consistency requires multiple episodes. Now
at a finer level the consistency check could be modeled at least 2 ways:
1) every conflicting/impasse causing episode gets chunked, and the
consistent ones wall paper over the ones caused by inconsistent interactions,
or 2) some number of consistent interactions must actually occur before
chunk formation completes. The first implies nothing is ever discarded,
which was part of SOAR last time I cared to know (2 yrs. ago). Everything
is paved over, from the ruins of Rome to last year's cow path.
I don't like that model because of brain chemistry. Brain chemistry
looks roughly like short-term electro-chemical storage maintains info.
temporarily until synaptic structural change acquires long-term info.
Given that model, lack of consistency would = lack of support for
consistent electro-chemical activity long enough in duration to support
structural change, so there would be no saved trace of transient, inconsistent
learning; some degree of consistency is required to build a long term
structure. Granted the chunk may later be found to be inappropriate &
hard to get rid of (got any bad habits?), but formation requires more than
1 episode (except perhaps for cocaine addicts), and SOAR doesn't.

The "theoretical limit part of the question" is "computationally unreasonable"
for a system whose short-term storage capacity doesn't meet almost
unlimited demand brought on by single-episode chunking. SOAR assumes
unlimited capacity and ignores time.



Dale Parson, Bell Labs, dale@mhcnet.att.com

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|    "These words are too solid, they don't move fast enough           |
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|     Suzanne Vega                                                     |
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