On k-Mer-Based and Maximum Likelihood Estimation Algorithms for Trace Reconstruction

Fuente: arXiv
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Main Authors: Cheng, Kuan, Grigorescu, Elena, Li, Xin, Sudan, Madhu, Zhu, Minshen
Format: Preprint
Published: 2023
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_version_ 1866929225824468992
author Cheng, Kuan
Grigorescu, Elena
Li, Xin
Sudan, Madhu
Zhu, Minshen
author_facet Cheng, Kuan
Grigorescu, Elena
Li, Xin
Sudan, Madhu
Zhu, Minshen
contents The goal of the trace reconstruction problem is to recover a string $x\in\{0,1\}^n$ given many independent {\em traces} of $x$, where a trace is a subsequence obtained from deleting bits of $x$ independently with some given probability $p\in [0,1).$ A recent result of Chase (STOC 2021) shows how $x$ can be determined (in exponential time) from $\exp(\widetilde{O}(n^{1/5}))$ traces. This is the state-of-the-art result on the sample complexity of trace reconstruction. In this paper we consider two kinds of algorithms for the trace reconstruction problem. Our first, and technically more involved, result shows that any $k$-mer-based algorithm for trace reconstruction must use $\exp(Ω(n^{1/5}))$ traces, under the assumption that the estimator requires $poly(2^k, 1/\varepsilon)$ traces, thus establishing the optimality of this number of traces. The analysis of this result also shows that the analysis technique used by Chase (STOC 2021) is essentially tight, and hence new techniques are needed in order to improve the worst-case upper bound. Our second, simple, result considers the performance of the Maximum Likelihood Estimator (MLE), which specifically picks the source string that has the maximum likelihood to generate the samples (traces). We show that the MLE algorithm uses a nearly optimal number of traces, \ie, up to a factor of $n$ in the number of samples needed for an optimal algorithm, and show that this factor of $n$ loss may be necessary under general ``model estimation'' settings.
format Preprint
id arxiv_https___arxiv_org_abs_2308_14993
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On k-Mer-Based and Maximum Likelihood Estimation Algorithms for Trace Reconstruction
Cheng, Kuan
Grigorescu, Elena
Li, Xin
Sudan, Madhu
Zhu, Minshen
Information Theory
The goal of the trace reconstruction problem is to recover a string $x\in\{0,1\}^n$ given many independent {\em traces} of $x$, where a trace is a subsequence obtained from deleting bits of $x$ independently with some given probability $p\in [0,1).$ A recent result of Chase (STOC 2021) shows how $x$ can be determined (in exponential time) from $\exp(\widetilde{O}(n^{1/5}))$ traces. This is the state-of-the-art result on the sample complexity of trace reconstruction. In this paper we consider two kinds of algorithms for the trace reconstruction problem. Our first, and technically more involved, result shows that any $k$-mer-based algorithm for trace reconstruction must use $\exp(Ω(n^{1/5}))$ traces, under the assumption that the estimator requires $poly(2^k, 1/\varepsilon)$ traces, thus establishing the optimality of this number of traces. The analysis of this result also shows that the analysis technique used by Chase (STOC 2021) is essentially tight, and hence new techniques are needed in order to improve the worst-case upper bound. Our second, simple, result considers the performance of the Maximum Likelihood Estimator (MLE), which specifically picks the source string that has the maximum likelihood to generate the samples (traces). We show that the MLE algorithm uses a nearly optimal number of traces, \ie, up to a factor of $n$ in the number of samples needed for an optimal algorithm, and show that this factor of $n$ loss may be necessary under general ``model estimation'' settings.
title On k-Mer-Based and Maximum Likelihood Estimation Algorithms for Trace Reconstruction
topic Information Theory
url https://arxiv.org/abs/2308.14993