### Abstract

We consider one-round games between a classical referee and two players. One of the main questions in this area is the parallel repetition question: Is there a way to decrease the maximum winning probability of a game without increasing the number of rounds or the number of players? Classically, efforts to resolve this question, open for many years, have culminated in Raz's celebrated parallel repetition theorem on one hand, and in efficient product testers for PCPs on the other. In the case where players share entanglement, the only previously known results are for special cases of games, and are based on techniques that seem inherently limited. Here we show for the first time that the maximum success probability of entangled games can be reduced through parallel repetition, provided it was not initially 1. Our proof is inspired by a seminal result of Feige and Kilian in the context of classical two-prover one-round interactive proofs. One of the main components in our proof is an orthogonalization lemma for operators, which might be of independent interest.

Original language | English (US) |
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Title of host publication | STOC'11 - Proceedings of the 43rd ACM Symposium on Theory of Computing |

Pages | 353-362 |

Number of pages | 10 |

DOIs | |

State | Published - 2011 |

Event | 43rd ACM Symposium on Theory of Computing, STOC'11 - San Jose, CA, United States Duration: Jun 6 2011 → Jun 8 2011 |

### Publication series

Name | Proceedings of the Annual ACM Symposium on Theory of Computing |
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ISSN (Print) | 0737-8017 |

### Other

Other | 43rd ACM Symposium on Theory of Computing, STOC'11 |
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Country | United States |

City | San Jose, CA |

Period | 6/6/11 → 6/8/11 |

### Keywords

- entangled games
- parallel repetition

### ASJC Scopus subject areas

- Software

## Cite this

*STOC'11 - Proceedings of the 43rd ACM Symposium on Theory of Computing*(pp. 353-362). (Proceedings of the Annual ACM Symposium on Theory of Computing). https://doi.org/10.1145/1993636.1993684