Parallel Repetition of Free Entangled Games: Simplification and Improvements
André Chailloux, Giannicola Scarpa
备注:
17 pages, this paper is a follow up and supersedes our previous paper 'Parallel Repetition of Entangled Games with Exponential Decay via the Superposed Information Cost' [CS14, arXiv:1310.7787] v2: updated GS affiliation
In a two-player game, two cooperating but non communicating players, Alice and Bob, receive inputs taken from a probability distribution. Each of them produces an output and they win the game if they satisfy some predicate on their inputs/outputs. The entangled value $ω^*(G)$ of a game $G$ is the maximum probability that Alice and Bob can win the game if they are allowed to share an entangled state prior to receiving their inputs.
The $n$-fold parallel repetition $G^n$ of $G$ consists of $n$ instances of $G$ where Alice and Bob receive all the inputs at the same time and must produce all the outputs at the same time. They win $G^n$ if they win each instance of $G$. Recently, there has been a series of works showing parallel repetition with exponential decay for projection games [DSV13], games on the uniform distribution [CS14] and for free games, i.e. games on a product distribution [JPY13].
This article is meant to be a follow up of [CS14], where we improve and simplify several parts of our previous paper. Our main result is that for any free game $G$ with value $ω^*(G)=1-\varepsilon$, we have $ω^*(G^n) \le (1 - \varepsilon^2)^{Ω(\frac{n}{\log(l)})}$ where $l$ is the size of the output set of the game. This result improves on both the results in [JPY13] and [CS14]. The framework we use can also be extended to free projection games. We show that for a free projection game $G$ with value $ω^*(G)=1-\varepsilon$, we have $ω^*(G^n) \le (1 - \varepsilon)^{Ω(n)}$.
Parallel repetition: simplifications and the no-signaling case
考虑一个游戏,其中裁判根据公开已知的分布P_XY选择(x,y),将x发送给Alice,将y发送给Bob。在没有相互通信的情况下,Alice用值“a”响应,Bob用值“b”响应。如果一个公知的谓词Q(x,y,a,b)成立,则Alice和Bob共同获胜。让我们给出这样一个博弈,并假设Alice和Bob获胜的最大概率是v<1。Raz(SIAM J. Comput. 27,1998)表明,如果游戏并行重复n次,则Alice和Bob同时赢得所有游戏的概率至多为v '^(n/log(s)),其中s是初始游戏中Alice和Bob可能响应的最大数量,v'是仅取决于v的常数。此外,我们研究的情况下,爱丽丝和鲍勃不限于本地计算,可以使用任何策略,这并不意味着他们之间的通信。
Guess your neighbor's input: Quantum advantage in Feige's game
Ruhr University Bochum(波鸿鲁尔大学);University of Copenhagen(哥本哈根大学);Ludwig-Maximilians-Universität München(慕尼黑路德维希-马克西米利安大学);Korteweg-de Vries Institute for Mathematics, University of Amsterdam(阿姆斯特丹大学科特韦格-德弗里斯数学研究所)