Abstract
We study asymmetric stochastic networks from two points of view: combinatorial optimization and learning algorithms based on relative entropy minimization. We show that there are non trivial classes of asymmetric networks which admit a Lyapunov function ℒ under deterministic parallel evolution and prove that the stochastic augmentation of such networks amounts to a stochastic search for global minima of ℒ. The problem of minimizing ℒ for a totally antisymmetric parallel network is shown to be associated to an NP-complete decision problem. The study of entropic learning for general asymmetric networks, performed in the non equilibrium, time dependent formalism, leads to a Hebbian rule based on time averages over the past history of the system. The general algorithm for asymmetric networks is tested on a feed-forward architecture.
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This research was supported in part by C.N.R. under grants 88.03556.12 and 89.05261.CT12
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Apolloni, B., Bertoni, A., Campadelli, P. et al. Asymmetric Boltzmann machines. Biol. Cybern. 66, 61–70 (1991). https://doi.org/10.1007/BF00196453
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DOI: https://doi.org/10.1007/BF00196453