Second-Order, First-Class: A Composable Stack for Curvature-Aware Training

Fuente: arXiv
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Main Authors: Korbit, Mikalai, Zanon, Mario
Format: Preprint
Published: 2026
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author Korbit, Mikalai
Zanon, Mario
author_facet Korbit, Mikalai
Zanon, Mario
contents Second-order methods promise improved stability and faster convergence, yet they remain underused due to implementation overhead, tuning brittleness, and the lack of composable APIs. We introduce Somax, a composable Optax-native stack that treats curvature-aware training as a single JIT-compiled step governed by a static plan. Somax exposes first-class modules -- curvature operators, estimators, linear solvers, preconditioners, and damping policies -- behind a single step interface and composes with Optax by applying standard gradient transformations (e.g., momentum, weight decay, schedules) to the computed direction. This design makes typically hidden choices explicit and swappable. Somax separates planning from execution: it derives a static plan (including cadences) from module requirements, then runs the step through a specialized execution path that reuses intermediate results across modules. We report system-oriented ablations showing that (i) composition choices materially affect scaling behavior and time-to-accuracy, and (ii) planning reduces per-step overhead relative to unplanned composition with redundant recomputation.
format Preprint
id arxiv_https___arxiv_org_abs_2603_25976
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Second-Order, First-Class: A Composable Stack for Curvature-Aware Training
Korbit, Mikalai
Zanon, Mario
Machine Learning
Second-order methods promise improved stability and faster convergence, yet they remain underused due to implementation overhead, tuning brittleness, and the lack of composable APIs. We introduce Somax, a composable Optax-native stack that treats curvature-aware training as a single JIT-compiled step governed by a static plan. Somax exposes first-class modules -- curvature operators, estimators, linear solvers, preconditioners, and damping policies -- behind a single step interface and composes with Optax by applying standard gradient transformations (e.g., momentum, weight decay, schedules) to the computed direction. This design makes typically hidden choices explicit and swappable. Somax separates planning from execution: it derives a static plan (including cadences) from module requirements, then runs the step through a specialized execution path that reuses intermediate results across modules. We report system-oriented ablations showing that (i) composition choices materially affect scaling behavior and time-to-accuracy, and (ii) planning reduces per-step overhead relative to unplanned composition with redundant recomputation.
title Second-Order, First-Class: A Composable Stack for Curvature-Aware Training
topic Machine Learning
url https://arxiv.org/abs/2603.25976