### Abstract

The multireference alignment problem consists of estimating a signal from multiple noisy shifted observations. Inspired by existing Unique-Games approximation algorithms, we provide a semidefinite program (SDP) based relaxation which approximates the maximum likelihood estimator (MLE) for the multireference alignment problem. Although we show this MLE problem is Unique-Games hard to approximate within any constant, we observe that our poly-time approximation algorithm for this problem appears to perform quite well in typical instances, outperforming existing methods. In an attempt to explain this behavior we provide stability guarantees for our SDP under a random noise model on the observations. This case is more challenging to analyze than traditional semi-random instances of Unique-Games: the noise model is on vertices of a graph and translates into dependent noise on the edges. Interestingly, we show that if certain positivity constraints in the relaxation are dropped, its solution becomes equivalent to performing phase correlation, a popular method used for pairwise alignment in imaging applications. Finally, we describe how symmetry reduction techniques from matrix representation theory can greatly decrease the computational cost of the SDP considered.

Original language | English (US) |
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Title of host publication | ITCS 2014 - Proceedings of the 2014 Conference on Innovations in Theoretical Computer Science |

Publisher | Association for Computing Machinery |

Pages | 459-470 |

Number of pages | 12 |

ISBN (Print) | 9781450322430 |

DOIs | |

State | Published - 2014 |

Event | 2014 5th Conference on Innovations in Theoretical Computer Science, ITCS 2014 - Princeton, NJ, United States Duration: Jan 12 2014 → Jan 14 2014 |

### Publication series

Name | ITCS 2014 - Proceedings of the 2014 Conference on Innovations in Theoretical Computer Science |
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### Other

Other | 2014 5th Conference on Innovations in Theoretical Computer Science, ITCS 2014 |
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Country | United States |

City | Princeton, NJ |

Period | 1/12/14 → 1/14/14 |

### Keywords

- Multireference alignment
- Phase correlation
- Semidefinite relaxation
- Unique-games

### ASJC Scopus subject areas

- Computational Theory and Mathematics

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## Cite this

*ITCS 2014 - Proceedings of the 2014 Conference on Innovations in Theoretical Computer Science*(pp. 459-470). (ITCS 2014 - Proceedings of the 2014 Conference on Innovations in Theoretical Computer Science). Association for Computing Machinery. https://doi.org/10.1145/2554797.2554839