Minimizing the Quadratic Training Error of a Sigmoid Neuron Is Hard

  • Authors:
  • Jirí Síma

  • Affiliations:
  • -

  • Venue:
  • ALT '01 Proceedings of the 12th International Conference on Algorithmic Learning Theory
  • Year:
  • 2001

Quantified Score

Hi-index 0.01

Visualization

Abstract

We first present a brief survey of hardness results for training feedforward neural networks. These results are then completed by the proof that the simplest architecture containing only a single neuron that applies the standard (logistic) activation function to the weighted sum of n inputs is hard to train. In particular, the problem of finding the weights of such a unit that minimize the relative quadratic training error within 1 or its average (over a training set) within 13/(31n) of its infimum proves to be NP-hard. Hence, the well-known back-propagation learning algorithm appears to be not efficient even for one neuron which has negative consequences in constructive learning.