arXiv Machine Learning By Patrick Inoue

Approaching Backpropagation Accuracy with Weight Perturbation on MNIST

Read the original on arXiv Machine Learning →

The paper investigates weight perturbation (WP) as a derivative-free alternative to backpropagation for training fully connected MNIST networks. In shallow architectures, large-batch WP attains about 97% test accuracy, close to backpropagation, but under a ten‑epoch budget WP lags behind (90.2% vs. 97.4%). The study also shows diminishing returns beyond a batch size of 4,000 and that learning‑rate reduction and averaging of perturbation updates can stabilize deeper networks, though they do not yet match backpropagation accuracy.

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arXiv Machine Learning
Sep 24

The Drift Contract: Spectral Updates for Depth-Robust Local Learning

The paper introduces the Drift Contract, a spectral update geometry for local learning that improves depth robustness and hyperparameter stability. By applying momentum orthogonalization with spectral step scaling to per‑layer updates, the authors achieve consistent performance across a wide range of widths and depths on CIFAR‑10 MLPs, outperforming local Adam and providing a per‑layer, input‑conditioned drift bound. The study also shows that the spectral geometry itself, rather than step‑size rules, drives the observed depth robustness, while a negative result indicates that the stability benefit is limited to non‑normalized layers.

By Fabien Polly
arXiv Machine Learning
Sep 11

ExpTest: Loss-Curve Hypothesis Testing for Autonomous Learning-Rate Selection in Deep Neural Networks

ExpTest is an autonomous learning‑rate controller that uses the training loss curve as an online signal to perform sequential statistical tests on theoretically motivated windows, detecting convergent behavior and triggering learning‑rate reductions. It combines a covariance‑based initial learning‑rate estimate, curvature‑motivated window sizing, and a two‑phase test‑driven decay, relying on the approximately exponential decay predicted under linearized network dynamics. Experiments on regression, classification, forecasting, and natural‑language tasks across various architectures show that ExpTest achieves competitive performance compared to hand‑tuned SGD baselines and recent learning‑rate‑free methods, without requiring manual initial learning‑rate selection or predefined scheduling.

By Zan Chaudhry, Naoko Mizuno