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		<title>WikiSysop: Created page with &quot;== Citation ==  Bendory, Tamir / Mickelin, Oscar / Singer, Amit. Sparse multi-reference alignment: Sample complexity and computational hardness. 2022. ICASSP 2022-2022 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), p. 8977-8981  == Abstract ==   Motivated by the problem of determining the atomic structure of macromolecules using single-particle cryo-electron microscopy (cryo-EM), we study the sample and computational complexities of th...&quot;</title>
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		<summary type="html">&lt;p&gt;Created page with &amp;quot;== Citation ==  Bendory, Tamir / Mickelin, Oscar / Singer, Amit. Sparse multi-reference alignment: Sample complexity and computational hardness. 2022. ICASSP 2022-2022 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), p. 8977-8981  == Abstract ==   Motivated by the problem of determining the atomic structure of macromolecules using single-particle cryo-electron microscopy (cryo-EM), we study the sample and computational complexities of th...&amp;quot;&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;== Citation ==&lt;br /&gt;
&lt;br /&gt;
Bendory, Tamir / Mickelin, Oscar / Singer, Amit. Sparse multi-reference alignment: Sample complexity and computational hardness. 2022. ICASSP 2022-2022 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), p. 8977-8981&lt;br /&gt;
&lt;br /&gt;
== Abstract ==&lt;br /&gt;
&lt;br /&gt;
 Motivated by the problem of determining the atomic structure of&lt;br /&gt;
macromolecules using single-particle cryo-electron microscopy&lt;br /&gt;
(cryo-EM), we study the sample and computational complexities&lt;br /&gt;
of the sparse multi-reference alignment (MRA) model: the problem&lt;br /&gt;
of estimating a sparse signal from its noisy, circularly shifted&lt;br /&gt;
copies. Based on its tight connection to the crystallographic phase&lt;br /&gt;
retrieval problem, we establish that if the number of observations&lt;br /&gt;
is proportional to the square of the variance of the noise, then the&lt;br /&gt;
sparse MRA problem is statistically feasible for sufficiently sparse&lt;br /&gt;
signals. To investigate its computational hardness, we consider&lt;br /&gt;
three types of computational frameworks: projection-based algorithms,&lt;br /&gt;
bispectrum inversion, and convex relaxations. We show that&lt;br /&gt;
a state-of-the-art projection-based algorithm achieves the optimal&lt;br /&gt;
estimation rate, but its computational complexity is exponential in&lt;br /&gt;
the sparsity level. The bispectrum framework provides a statisticalcomputational&lt;br /&gt;
trade-off: it requires more observations (so its estimation&lt;br /&gt;
rate is suboptimal), but its computational load is provably&lt;br /&gt;
polynomial in the signal’s length. The convex relaxation approach&lt;br /&gt;
provides polynomial-time algorithms (with a large exponent) that&lt;br /&gt;
recover sufficiently sparse signals at the optimal estimation rate. We&lt;br /&gt;
conclude the paper by discussing potential statistical and algorithmic&lt;br /&gt;
implications for cryo-EM.&lt;br /&gt;
&lt;br /&gt;
== Keywords ==&lt;br /&gt;
&lt;br /&gt;
== Links ==&lt;br /&gt;
&lt;br /&gt;
https://ieeexplore.ieee.org/abstract/document/9746298&lt;br /&gt;
&lt;br /&gt;
== Related software ==&lt;br /&gt;
&lt;br /&gt;
== Related methods ==&lt;br /&gt;
&lt;br /&gt;
== Comments ==&lt;/div&gt;</summary>
		<author><name>WikiSysop</name></author>
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