Practical colinear chaining on sequences revisited

Fuente: arXiv
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Hauptverfasser: Rizzo, Nicola, Cáceres, Manuel, Mäkinen, Veli
Format: Preprint
Veröffentlicht: 2025
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author Rizzo, Nicola
Cáceres, Manuel
Mäkinen, Veli
author_facet Rizzo, Nicola
Cáceres, Manuel
Mäkinen, Veli
contents Colinear chaining is a classical heuristic for sequence alignment and is widely used in modern practical aligners. Jain et al. (J. Comput. Biol. 2022) proposed an $O(n \log^3 n)$ time algorithm to chain a set of $n$ anchors so that the chaining cost matches the edit distance of the input sequences, when anchors are all the maximal exact matches. Moreover, assuming a uniform and sparse distribution of anchors, they provided a practical solution ($\mathtt{ChainX}$) working in $O(n \cdot \mathrm{SOL} + n \log n)$ average-case time, where $\mathrm{SOL}$ is the cost of the output chain. This practical solution is not guaranteed to be optimal: we study the failing cases, introduce the anchor diagonal distance, and find and implement an optimal algorithm working in $O(n \cdot \mathrm{OPT} + n \log n)$ average-case time, where $\mathrm{OPT}$ $\le \mathrm{SOL}$ is the optimal chaining cost. We validate the results by Jain et al., show that $\mathtt{ChainX}$ can be suboptimal with a realistic long read dataset, and show minimal computational slowdown for our solution.
format Preprint
id arxiv_https___arxiv_org_abs_2506_11750
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Practical colinear chaining on sequences revisited
Rizzo, Nicola
Cáceres, Manuel
Mäkinen, Veli
Data Structures and Algorithms
Colinear chaining is a classical heuristic for sequence alignment and is widely used in modern practical aligners. Jain et al. (J. Comput. Biol. 2022) proposed an $O(n \log^3 n)$ time algorithm to chain a set of $n$ anchors so that the chaining cost matches the edit distance of the input sequences, when anchors are all the maximal exact matches. Moreover, assuming a uniform and sparse distribution of anchors, they provided a practical solution ($\mathtt{ChainX}$) working in $O(n \cdot \mathrm{SOL} + n \log n)$ average-case time, where $\mathrm{SOL}$ is the cost of the output chain. This practical solution is not guaranteed to be optimal: we study the failing cases, introduce the anchor diagonal distance, and find and implement an optimal algorithm working in $O(n \cdot \mathrm{OPT} + n \log n)$ average-case time, where $\mathrm{OPT}$ $\le \mathrm{SOL}$ is the optimal chaining cost. We validate the results by Jain et al., show that $\mathtt{ChainX}$ can be suboptimal with a realistic long read dataset, and show minimal computational slowdown for our solution.
title Practical colinear chaining on sequences revisited
topic Data Structures and Algorithms
url https://arxiv.org/abs/2506.11750