Dimension-Free Bounds for Generalized First-Order Methods via Gaussian Coupling
- URL: http://arxiv.org/abs/2508.10782v1
- Date: Thu, 14 Aug 2025 16:08:01 GMT
- Title: Dimension-Free Bounds for Generalized First-Order Methods via Gaussian Coupling
- Abstract summary: We establish non-asymptotic bounds on the finite-sample of generalized first-order iterative algorithms.<n>We construct an explicit coupling between the iterates of a generalized first-order method and a conditionally Gaussian process.<n>This coupling yields tight, dimension-free bounds under mild Lipschitz and moment-matching conditions.
- Score: 6.402504044106936
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: We establish non-asymptotic bounds on the finite-sample behavior of generalized first-order iterative algorithms -- including gradient-based optimization methods and approximate message passing (AMP) -- with Gaussian data matrices and full-memory, non-separable nonlinearities. The central result constructs an explicit coupling between the iterates of a generalized first-order method and a conditionally Gaussian process whose covariance evolves deterministically via a finite-dimensional state evolution recursion. This coupling yields tight, dimension-free bounds under mild Lipschitz and moment-matching conditions. Our analysis departs from classical inductive AMP proofs by employing a direct comparison between the generalized first-order method and the conditionally Gaussian comparison process. This approach provides a unified derivation of AMP theory for Gaussian matrices without relying on separability or asymptotics. A complementary lower bound on the Wasserstein distance demonstrates the sharpness of our upper bounds.
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