Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!usc!snorkelwacker!bloom-beacon!eru!luth!sunic!mcsun!hp4nl!ruuinf!praxis!jagversm
From: jagversm@praxis.cs.ruu.nl (Koen Versmissen)
Newsgroups: comp.ai.neural-nets
Subject: Harmony theory - looking for references and clues
Keywords: Harmony theory, probabilistic units, symmetry
Message-ID: <2693@ruuinf.cs.ruu.nl>
Date: 20 Mar 90 10:34:09 GMT
Sender: news@ruuinf.cs.ruu.nl
Lines: 30

I'm to give a talk in a seminar on neural nets shortly, and I thought
Harmony theory would be an interesting subject. I have a few questions
though:
- I only know harmony theory through Paul Smolensky's chapter in the
  Rumelhart & McClelland PDP-book. What have been the developments
  since? References to important articles would be most welcome (even
  though it may be too late for me to use them in the preparation of
  my talk).
- I hope someone can shed some light on something that I found 
  particlularly puzzling in Smolensky's article:
  Harmony theory claims to be psychologically relevant ("... these
  dynamical systems can serve as models of human cognition", p. 195).
  Now neurons are not (or at best hardly) probabilistic, right? How
  then can harmony theory claim to provide a _micro-level_ description
  of the mind? Shouldn't it rather be called an _intermediate level_
  description? After all, an account of how probabilistic units can be
  implemented (or rather, simulated) by means of, say, deterministic 
  threshold units, is still needed.
  Does all this make some sense?
  (N.B. even though Smolensky stresses the importance of taking small
   steps, I find it strange that he didn't mention the above issue at
   all).
- The same question as the above, but now concerning symmetric
  connections in Harmony theory, as opposed to asymmetry in the brain.

Koen

----------------------------------------------------------------------
Koen Versmissen
(jagversm@praxis.cs.ruu.nl)