Density of states in neural networks: an in-depth exploration of learning in parameter space

Learning in neural networks critically hinges on the intricate geometry of the loss landscape associated with a given task. Traditionally, most research has focused on finding specific weight configurations that minimize the loss. In this work, born from the cross-fertilization of machine learning and theoretical soft matter physics, we introduce a novel approach to examine the weight space across all loss values. Employing the Wang-Landau enhanced sampling algorithm, we explore the neural network density of states – the number of network parameter configurations that produce a given loss value – and analyze how it depends on specific features of the training set. Using both real-world and synthetic data, we quantitatively elucidate the relation between data structure and network density of states across different sizes and depths of binary-state networks. This work presents and illustrates a novel, informative analysis method that aims at paving the way for a better understanding of the interplay between structured data and the networks that process, learn, and generate them.