Geometric Regularization in Mixture-of-Experts: The Disconnect Between Weights and Activations

Fuente: arXiv
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Autor principal: Kim, Hyunjun
Formato: Preprint
Publicado: 2026
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author Kim, Hyunjun
author_facet Kim, Hyunjun
contents Mixture-of-Experts (MoE) models achieve efficiency through sparse activation, but the role of geometric regularization in expert specialization remains unclear. We apply orthogonality loss to enforce expert diversity and find it fails on multiple fronts: it does not reduce weight-space overlap (MSO actually increases by up to 114%), activation-space overlap remains high (~0.6) regardless of regularization, and effects on performance are inconsistent -- marginal improvement on WikiText-103 (-0.9%), slight degradation on TinyStories (+0.9%), and highly variable results on PTB (std > 1.0). Our analysis across 7 regularization strengths reveals no significant correlation (r = -0.293, p = 0.523) between weight and activation orthogonality. These findings demonstrate that weight-space regularization neither achieves its geometric goal nor reliably improves performance, making it unsuitable for MoE diversity.
format Preprint
id arxiv_https___arxiv_org_abs_2601_00457
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Geometric Regularization in Mixture-of-Experts: The Disconnect Between Weights and Activations
Kim, Hyunjun
Machine Learning
Artificial Intelligence
Mixture-of-Experts (MoE) models achieve efficiency through sparse activation, but the role of geometric regularization in expert specialization remains unclear. We apply orthogonality loss to enforce expert diversity and find it fails on multiple fronts: it does not reduce weight-space overlap (MSO actually increases by up to 114%), activation-space overlap remains high (~0.6) regardless of regularization, and effects on performance are inconsistent -- marginal improvement on WikiText-103 (-0.9%), slight degradation on TinyStories (+0.9%), and highly variable results on PTB (std > 1.0). Our analysis across 7 regularization strengths reveals no significant correlation (r = -0.293, p = 0.523) between weight and activation orthogonality. These findings demonstrate that weight-space regularization neither achieves its geometric goal nor reliably improves performance, making it unsuitable for MoE diversity.
title Geometric Regularization in Mixture-of-Experts: The Disconnect Between Weights and Activations
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2601.00457