Understanding Optimal Portfolios of Strategies for Solving Two-player Zero-sum Games

Fuente: arXiv
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Main Authors: Drabent, Karolina, Kubíček, Ondřej, Lisý, Viliam
Format: Preprint
Published: 2025
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author Drabent, Karolina
Kubíček, Ondřej
Lisý, Viliam
author_facet Drabent, Karolina
Kubíček, Ondřej
Lisý, Viliam
contents In large-scale games, approximating the opponent's strategy space with a small portfolio of representative strategies is a common and powerful technique. However, the construction of these portfolios often relies on domain-specific knowledge or heuristics with no theoretical guarantees. This paper establishes a formal foundation for portfolio-based strategy approximation. We define the problem of finding an optimal portfolio in two-player zero-sum games and prove that this optimization problem is NP-hard. We demonstrate that several intuitive heuristics-such as using the support of a Nash Equilibrium or building portfolios incrementally - can lead to highly suboptimal solutions. These negative results underscore the problem's difficulty and motivate the need for robust, empirically-validated heuristics. To this end, we introduce an analytical framework to bound portfolio quality and propose a methodology for evaluating heuristic approaches. Our evaluation of several heuristics shows that their success heavily depends on the specific game being solved. Our code is publicly available.
format Preprint
id arxiv_https___arxiv_org_abs_2511_18658
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Understanding Optimal Portfolios of Strategies for Solving Two-player Zero-sum Games
Drabent, Karolina
Kubíček, Ondřej
Lisý, Viliam
Computer Science and Game Theory
In large-scale games, approximating the opponent's strategy space with a small portfolio of representative strategies is a common and powerful technique. However, the construction of these portfolios often relies on domain-specific knowledge or heuristics with no theoretical guarantees. This paper establishes a formal foundation for portfolio-based strategy approximation. We define the problem of finding an optimal portfolio in two-player zero-sum games and prove that this optimization problem is NP-hard. We demonstrate that several intuitive heuristics-such as using the support of a Nash Equilibrium or building portfolios incrementally - can lead to highly suboptimal solutions. These negative results underscore the problem's difficulty and motivate the need for robust, empirically-validated heuristics. To this end, we introduce an analytical framework to bound portfolio quality and propose a methodology for evaluating heuristic approaches. Our evaluation of several heuristics shows that their success heavily depends on the specific game being solved. Our code is publicly available.
title Understanding Optimal Portfolios of Strategies for Solving Two-player Zero-sum Games
topic Computer Science and Game Theory
url https://arxiv.org/abs/2511.18658