Score: 0

Source-Optimal Training is Transfer-Suboptimal

Published: November 11, 2025 | arXiv ID: 2511.08401v1

By: C. Evans Hedges

Potential Business Impact:

Improves computer learning by finding the best way to teach it.

Business Areas:
A/B Testing Data and Analytics

We prove a fundamental misalignment in transfer learning: the source regularization that minimizes source risk almost never coincides with the regularization maximizing transfer benefit. Through sharp phase boundaries for L2-SP ridge regression, we characterize the transfer-optimal source penalty $τ_0^*$ and show it diverges predictably from task-optimal values, requiring stronger regularization in high-SNR regimes and weaker regularization in low-SNR regimes. Additionally, in isotropic settings the decision to transfer is remarkably independent of target sample size and noise, depending only on task alignment and source characteristics. CIFAR-10 and MNIST experiments confirm this counterintuitive pattern persists in non-linear networks.

Page Count
17 pages

Category
Statistics:
Machine Learning (Stat)