tech report announcement

[Dave.Touretzky@B.GP.CS.CMU.EDU]

     A Connectionist Implementation of Cognitive Phonology

                  Deirdre W. Wheeler [1]
                  David S. Touretzky [2]


[1] Department of Linguistics	 [2] School of Computer Science
    University of Pittsburgh          Carnegie Mellon University
    Pittsburgh, PA 15260              Pittsburgh, PA  15213


 	     Technical report number CMU-CS-89-144



			  ABSTRACT

This paper reports on an initial implementation of Lakoff's theory of
cognitive phonology in a connectionist network.  Standard generative
phonological theories require serial application of rules, which results in
derivations with numerous intermediate states.  This is incompatible with
the connectionist goals of psychological and biological plausibility, and
may also hinder learnability.  Lakoff's theory of cognitive phonology
offers a solution to some of these problems by providing an alternative way
to think about derivations and ordered rules, and by eliminating the need
for right-to-left iterative rule application.  On the other hand, Lakoff's
proposal presents certain computational difficulties due to its appeal to
Harmony Theory.  We present a reformulation of cognitive phonology using a
novel clustering mechanism that completely eliminates iteration and permits
an efficient feed-forward implementation.

An earlier version of this paper was presented at the Berkeley Workshop on
Constraints vs. Rules in Phonology, May 26-27, 1989.

Note: the version of the system described in this report is considerably
more refined than the version in the 1989 Cognitive Science Conference
paper and the "Rules and Maps" tech report.

The following abstract for a talk I've been giving recently at various
institutions may better explain why this material should be of interest
to cognitive scientists, not just linguists:

		    A COMPUTATIONAL BASIS FOR PHONOLOGY

   Phonology is the study of the sound patterns of a language.  It includes
processes such as nasal assimilation, vowel harmony, tone shifting, and
syllabification.  The phonological structure of human languages is
intricate, but it is also highly constrained and stunningly regular.  The
easy observability of phonological processes, their discrete, symbolic
nature, and their rapid acquisition by very young children suggest that
this may be a good domain in which to explore issues of rules and symbolic
representations in the brain.

    In this talk I will give a brief sketch of George Lakoff's new theory
of cognitive phonology, in which sequential derivations are eliminated by
having all rules apply in parallel.  I will then describe how our attempt
to construct a connectionist implementation of the theory led us to revise
it in significant ways.  The architecture we developed resulted in a novel
prediction of a constraint on insertion processes.  Subsequent
consultations with expert phonologists have so far confirmed this
prediction.  If correct, it represents the first step toward our long term
goal of developing a computational explanation for why phonology looks the
way it does.


----------------------------------------------------------------

HOW TO ORDER THIS REPORT:

Copies of the report are available by writing to Ms. Catherine Copetas,
School of Computer Science, Carnegie Mellon University, Pittsburgh, PA
15213.  Email requests may be sent to copetas at cs.cmu.edu.  Ask for report
number CMU-CS-89-144.  There is no charge for this report.