(New Tech. Report) From Simple Associations to Systematic Reasoning

[shastri@central.cis.upenn.edu]

The following report may be of interest to some of you. Please direct e-mail
requests to: dawn at central.cis.upenn.edu

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


		From Simple Associations to Systematic Reasoning:  

    A connectionist representation of rules, variables and dynamic bindings


	   	  Lokendra Shastri and Venkat Ajjanagadde
		Computer and Information Science Department
			University of Pennsylvania
			Philadelphia, PA  19104

  			    December 1989

  Human agents draw a variety of inferences effortlessly, spontaneously, 
  and with remarkable efficiency --- as though these inferences are a  
  reflex response of their cognitive apparatus.  The work presented in
  this paper is a step toward a computational account of this remarkable
  reasoning ability. We describe how a connectionist system made up of
  simple and slow neuron-like elements can encode millions of facts and
  rules involving n-ary predicates and variables, and yet perform a
  variety of inferences within hundreds of milliseconds. We observe that
  an efficient reasoning system must represent and propagate, dynamically,
  a large number of variable bindings. The proposed system does so by
  propagating rhythmic patterns of activity wherein dynamic bindings are
  represented as the in-phase, i.e., synchronous, firing of appropriate
  nodes. The mechanisms for representing and propagating dynamic bindings
  are biologically plausible.  Neurophysiological evidence suggests that
  similar mechanisms may in fact be used by the brain to represent and
  process sensorimotor information.