On finite-horizon approximation of a feedback Nash equilibrium in LQ games

Fuente: arXiv
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Main Authors: Huang, Shengyuan, Yang, Xiaoguang, Mu, Yifen, Mei, Wenjun
Format: Preprint
Published: 2025
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author Huang, Shengyuan
Yang, Xiaoguang
Mu, Yifen
Mei, Wenjun
author_facet Huang, Shengyuan
Yang, Xiaoguang
Mu, Yifen
Mei, Wenjun
contents Dynamic games provide a fundamental framework for multi-agent decision-making over time, yet computing feedback Nash equilibria (FNEs) in infinite-horizon discrete-time linear-quadratic (LQ) settings remains computationally challenging. Motivated by the need for tractable and implementable strategies, this paper studies a finite-horizon strategy for approximating a certain infinite-horizon equilibrium. Specifically, at each stage, each player solves a T-stage game and implements only the first-stage control, thereby avoiding the direct solution of coupled infinite-horizon Riccati equations. We first analyze the finite-horizon game and characterize the structure of the associated coupled generalized discrete Riccati difference equations. Based on this analysis, we establish a sufficient condition for uniqueness of the FNE and propose an efficient algorithm that computes it via a sequence of linear equations. We then consider the infinite-horizon game in which players adopt the finite-horizon strategies with heterogeneous prediction horizons and show that, under suitable conditions, the total cost under the finite-horizon strategies converges to the cost under the limiting infinite-horizon FNE. Moreover, we derive an explicit upper bound on this cost gap in terms of the distance between the corresponding strategy matrices. These results provide theoretical justification and quantitative performance guarantees for finite-horizon strategies in infinite-horizon LQ dynamic games. A nonscalar numerical example illustrates the effectiveness of the proposed framework.
format Preprint
id arxiv_https___arxiv_org_abs_2506_19565
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On finite-horizon approximation of a feedback Nash equilibrium in LQ games
Huang, Shengyuan
Yang, Xiaoguang
Mu, Yifen
Mei, Wenjun
Systems and Control
Optimization and Control
Dynamic games provide a fundamental framework for multi-agent decision-making over time, yet computing feedback Nash equilibria (FNEs) in infinite-horizon discrete-time linear-quadratic (LQ) settings remains computationally challenging. Motivated by the need for tractable and implementable strategies, this paper studies a finite-horizon strategy for approximating a certain infinite-horizon equilibrium. Specifically, at each stage, each player solves a T-stage game and implements only the first-stage control, thereby avoiding the direct solution of coupled infinite-horizon Riccati equations. We first analyze the finite-horizon game and characterize the structure of the associated coupled generalized discrete Riccati difference equations. Based on this analysis, we establish a sufficient condition for uniqueness of the FNE and propose an efficient algorithm that computes it via a sequence of linear equations. We then consider the infinite-horizon game in which players adopt the finite-horizon strategies with heterogeneous prediction horizons and show that, under suitable conditions, the total cost under the finite-horizon strategies converges to the cost under the limiting infinite-horizon FNE. Moreover, we derive an explicit upper bound on this cost gap in terms of the distance between the corresponding strategy matrices. These results provide theoretical justification and quantitative performance guarantees for finite-horizon strategies in infinite-horizon LQ dynamic games. A nonscalar numerical example illustrates the effectiveness of the proposed framework.
title On finite-horizon approximation of a feedback Nash equilibrium in LQ games
topic Systems and Control
Optimization and Control
url https://arxiv.org/abs/2506.19565