Analyzing and Enhancing the Backward-Pass Convergence of Unrolled Optimization

Fuente: arXiv
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Main Authors: Kotary, James, Christopher, Jacob, Dinh, My H, Fioretto, Ferdinando
Format: Preprint
Published: 2023
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author Kotary, James
Christopher, Jacob
Dinh, My H
Fioretto, Ferdinando
author_facet Kotary, James
Christopher, Jacob
Dinh, My H
Fioretto, Ferdinando
contents The integration of constrained optimization models as components in deep networks has led to promising advances on many specialized learning tasks. A central challenge in this setting is backpropagation through the solution of an optimization problem, which often lacks a closed form. One typical strategy is algorithm unrolling, which relies on automatic differentiation through the entire chain of operations executed by an iterative optimization solver. This paper provides theoretical insights into the backward pass of unrolled optimization, showing that it is asymptotically equivalent to the solution of a linear system by a particular iterative method. Several practical pitfalls of unrolling are demonstrated in light of these insights, and a system called Folded Optimization is proposed to construct more efficient backpropagation rules from unrolled solver implementations. Experiments over various end-to-end optimization and learning tasks demonstrate the advantages of this system both computationally, and in terms of flexibility over various optimization problem forms.
format Preprint
id arxiv_https___arxiv_org_abs_2312_17394
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Analyzing and Enhancing the Backward-Pass Convergence of Unrolled Optimization
Kotary, James
Christopher, Jacob
Dinh, My H
Fioretto, Ferdinando
Machine Learning
Optimization and Control
The integration of constrained optimization models as components in deep networks has led to promising advances on many specialized learning tasks. A central challenge in this setting is backpropagation through the solution of an optimization problem, which often lacks a closed form. One typical strategy is algorithm unrolling, which relies on automatic differentiation through the entire chain of operations executed by an iterative optimization solver. This paper provides theoretical insights into the backward pass of unrolled optimization, showing that it is asymptotically equivalent to the solution of a linear system by a particular iterative method. Several practical pitfalls of unrolling are demonstrated in light of these insights, and a system called Folded Optimization is proposed to construct more efficient backpropagation rules from unrolled solver implementations. Experiments over various end-to-end optimization and learning tasks demonstrate the advantages of this system both computationally, and in terms of flexibility over various optimization problem forms.
title Analyzing and Enhancing the Backward-Pass Convergence of Unrolled Optimization
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2312.17394