Unsupervised learning of echo state networks: a case study in artificial embryogeny

  • Authors:
  • Alexandre Devert;Nicolas Bredeche;Marc Schoenauer

  • Affiliations:
  • INRIA Futurs, LRI, CNRS, Université Paris-Sud, France;INRIA Futurs, LRI, CNRS, Université Paris-Sud, France;INRIA Futurs, LRI, CNRS, Université Paris-Sud, France

  • Venue:
  • EA'07 Proceedings of the Evolution artificielle, 8th international conference on Artificial evolution
  • Year:
  • 2007

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Abstract

Echo State Networks (ESN) have demonstrated their efficiencyin supervised learning of time series: a "reservoir" of neuronsprovide a set of dynamical systems that can be linearly combined tomatch the target dynamics, using a simple quadratic optimisation algorithmto tune the few free parameters. In an unsupervised learningcontext, however, another optimiser is needed. In this paper, an adaptive(1+1)-Evolution Strategy is used to optimise an ESN to tackle the"flag" problem, a classical benchmark from multi-cellular artificial embryogeny:the genotype is the cell controller of a Continuous CellularAutomata, and the phenotype, the image that corresponds to the fixed-point of the resulting dynamical system, must match a given 2D pattern.This approach is able to provide excellent results with few evaluations,and favourably compares to that using the NEAT algorithm (a state-of-the-art neuro-evolution method) to evolve the cell controllers. Somecharacteristics of the fitness landscape of the ESN-based method are alsoinvestigated.