Quantum strategies, error bounds, optimality, and duality gaps for multiplayer XOR, $\mathrm{XOR}^{*}$, compiled XOR, $\mathrm{XOR}^{*}$, and strong parallel repetiton of XOR, $\mathrm{XOR}^{*}$, and FFL games

TL;DR

This paper characterizes the optimality and quantum advantages in multiplayer XOR and related games, extending previous frameworks to more complex game variants and analyzing error bounds, duality gaps, and strategy spaces.

Contribution

It develops new methods for analyzing quantum strategies and error bounds in multiplayer XOR games and their variants, expanding the theoretical understanding of quantum advantages in complex game settings.

Findings

Characterization of exact and approximate optimality in multiplayer XOR games.

Extension of error bound construction to multiplayer and variant games.

Identification of quantum advantages in complex game-theoretic scenarios.

Abstract

We characterize exact, and approximate, optimality of games that players can interact with using quantum strategies. In comparison to a previous work of the author, arXiv: 2311.12887, which applied a 2016 framework due to Ostrev for constructing error bounds beyond CHSH and XOR games, in addition to the existence of well-posed semidefinite programs for determining primal feasible solutions, along with quantum-classical duality gaps, it continues to remain of interest to further develop the construction of error bounds, and related objects, to game-theoretic settings with several participants. In such settings, one encounters a rich information theoretic landscape, not only from the fact that there exists a significantly larger combinatorial space of possible strategies for each player, but also several opportunities for pronounced quantum advantage. We conclude this effort by describing other variants of other possible strategies, as proposed sources for quantum advantage, in $\mathrm{XOR}^{*}$, compiled $\mathrm{XOR}^{*}$, and strong parallel repetition variants of $\mathrm{XOR}^{*}$ games.