• Corpus ID: 242758274

Gardner formula for Ising perceptron models at small densities

@inproceedings{Bolthausen2021GardnerFF,
  title={Gardner formula for Ising perceptron models at small densities},
  author={Erwin Bolthausen and Shuta Nakajima and Nike Sun and Chang Xu},
  booktitle={Annual Conference Computational Learning Theory},
  year={2021}
}

• E. Bolthausen, S. Nakajima, +1 author Chang Xu
• Published in
  Annual Conference…
  4 November 2021
• Mathematics

We consider the Ising perceptron model with N spins and M = N*alpha patterns, with a general activation function U that is bounded above. For U bounded away from zero, or U a one-sided threshold function, it was shown by Talagrand (2000, 2011) that for small densities alpha, the free energy of the model converges in the large-N limit to the replica symmetric formula conjectured in the physics literature (Krauth--Mezard 1989, see also Gardner--Derrida 1988). We give a new proof of this result, which covers the more general class of all functions U that are bounded above and satisfy a certain variance bound. The proof uses the (first and second) moment method conditional on the approximate message passing iterates of the model. In order to deduce our main theorem, we also prove a new concentration result for the perceptron model in the case where U is not bounded away from zero.