Technical note on Sequential Test-Time Adaptation via Martingale-Driven Fisher Prompting

Fuente: arXiv
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Autores principales: Khan, Behraj, Syed, Tahir Qasim
Formato: Preprint
Publicado: 2025
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author Khan, Behraj
Syed, Tahir Qasim
author_facet Khan, Behraj
Syed, Tahir Qasim
contents We present a theoretical framework for M-FISHER, a method for sequential distribution shift detection and stable adaptation in streaming data. For detection, we construct an exponential martingale from non-conformity scores and apply Ville's inequality to obtain time-uniform guarantees on false alarm control, ensuring statistical validity at any stopping time. Under sustained shifts, we further bound the expected detection delay as $\mathcal{O}(\log(1/δ)/Γ)$, where $Γ$ reflects the post-shift information gain, thereby linking detection efficiency to distributional divergence. For adaptation, we show that Fisher-preconditioned updates of prompt parameters implement natural gradient descent on the distributional manifold, yielding locally optimal updates that minimize KL divergence while preserving stability and parameterization invariance. Together, these results establish M-FISHER as a principled approach for robust, anytime-valid detection and geometrically stable adaptation in sequential decision-making under covariate shift.
format Preprint
id arxiv_https___arxiv_org_abs_2510_03839
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Technical note on Sequential Test-Time Adaptation via Martingale-Driven Fisher Prompting
Khan, Behraj
Syed, Tahir Qasim
Machine Learning
We present a theoretical framework for M-FISHER, a method for sequential distribution shift detection and stable adaptation in streaming data. For detection, we construct an exponential martingale from non-conformity scores and apply Ville's inequality to obtain time-uniform guarantees on false alarm control, ensuring statistical validity at any stopping time. Under sustained shifts, we further bound the expected detection delay as $\mathcal{O}(\log(1/δ)/Γ)$, where $Γ$ reflects the post-shift information gain, thereby linking detection efficiency to distributional divergence. For adaptation, we show that Fisher-preconditioned updates of prompt parameters implement natural gradient descent on the distributional manifold, yielding locally optimal updates that minimize KL divergence while preserving stability and parameterization invariance. Together, these results establish M-FISHER as a principled approach for robust, anytime-valid detection and geometrically stable adaptation in sequential decision-making under covariate shift.
title Technical note on Sequential Test-Time Adaptation via Martingale-Driven Fisher Prompting
topic Machine Learning
url https://arxiv.org/abs/2510.03839