2023/12/06 by Pierre Wolinski, Wolinski, Pierre · 1 voice
Computer Science · #Machine Learning and Algorithms #Machine Learning and Data Classification #Neural Networks and Applications
paper · doi:10.1007/978-3-032-06078-5_25
openalex publication_date 2025/09/29 · crossref created 2025/09/29 · crossref deposited 2025/09/29 · crossref issued 2025/09/30 · crossref published 2025/09/30 · crossref published-online 2025/09/30 · crossref indexed 2025/09/30 · openalex created_date 2025/10/10 · crossref published-print 2026/01/01 · openalex updated_date 2026/07/29
When training large models, such as neural networks, the full derivatives of order 2 and beyond are usually inaccessible, due to their computational cost. Therefore, among the second-order optimization methods, it is common to bypass the computation of the Hessian by using first-order information, such as the gradient of the parameters (e.g., quasi-Newton methods) or the activations (e.g., K-FAC). In this paper, we focus on the exact and explicit computation of projections of the Hessian and higher-order derivatives on well-chosen subspaces relevant for optimization. Namely, for a given partition of the set of parameters, we compute tensors that can be seen as "higher-order derivatives according to the partition", at a reasonable cost as long as the number of subsets of the partition remains small. Then, we give some examples of how these tensors can be used. First, we show how to compute a learning rate per subset of parameters, which can be used for hyperparameter tuning. Second, we show how to use these tensors at order 2 to construct an optimization method that uses information contained in the Hessian. Third, we show how to use these tensors at order 3 (information contained in the third derivative of the loss) to regularize this optimization method. The resulting training step has several interesting properties, including: it takes into account long-range interactions between the layers of the trained neural network, which is usually not the case in similar methods (e.g., K-FAC); the trajectory of the optimization is invariant under affine layer-wise reparameterization.