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Main Author: Lal, Manish Krishan
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2512.23843
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author Lal, Manish Krishan
author_facet Lal, Manish Krishan
contents We study the Reflect-Reflect-Relax (RRR) algorithm in its small-step (flow-limit) regime. In the smooth transversal setting, we show that the transverse dynamics form a hyperbolic sink, yielding exponential decay of a natural gap measure. Under uniform geometric assumptions, we construct a tubular neighborhood of the feasible manifold on which the squared gap defines a strict Lyapunov function, excluding recurrent dynamics and chaotic behavior within this basin. In the discrete setting, the induced flow is piecewise constant on W-domains and supports Filippov sliding along convergent boundaries, leading to finite-time capture into a solution domain. We prove that small-step RRR is a forward-Euler discretization of this flow, so that solution times measured in rescaled units converge to a finite limit while iteration counts diverge, explaining the emergence of iteration-optimal relaxation parameters. Finally, we introduce a heuristic mesoscopic framework based on percolation and renormalization group to organize performance deterioration near the Douglas-Rachford limit.
format Preprint
id arxiv_https___arxiv_org_abs_2512_23843
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Flow-Limit of Reflect-Reflect-Relax: Existence, Stability, and Discrete-Time Behavior
Lal, Manish Krishan
Optimization and Control
Numerical Analysis
Dynamical Systems
Primary 37N40, Secondary 49J53, 90C30, 65K10
We study the Reflect-Reflect-Relax (RRR) algorithm in its small-step (flow-limit) regime. In the smooth transversal setting, we show that the transverse dynamics form a hyperbolic sink, yielding exponential decay of a natural gap measure. Under uniform geometric assumptions, we construct a tubular neighborhood of the feasible manifold on which the squared gap defines a strict Lyapunov function, excluding recurrent dynamics and chaotic behavior within this basin. In the discrete setting, the induced flow is piecewise constant on W-domains and supports Filippov sliding along convergent boundaries, leading to finite-time capture into a solution domain. We prove that small-step RRR is a forward-Euler discretization of this flow, so that solution times measured in rescaled units converge to a finite limit while iteration counts diverge, explaining the emergence of iteration-optimal relaxation parameters. Finally, we introduce a heuristic mesoscopic framework based on percolation and renormalization group to organize performance deterioration near the Douglas-Rachford limit.
title The Flow-Limit of Reflect-Reflect-Relax: Existence, Stability, and Discrete-Time Behavior
topic Optimization and Control
Numerical Analysis
Dynamical Systems
Primary 37N40, Secondary 49J53, 90C30, 65K10
url https://arxiv.org/abs/2512.23843