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We consider the longest common subsequence (LCS) problem with the restriction that the common subsequence is required to consist of at least $k$ length substrings. First, we show an $O(mn)$ time algorithm for the problem which gives a…

Data Structures and Algorithms · Computer Science 2017-02-07 Yohei Ueki , Diptarama , Masatoshi Kurihara , Yoshiaki Matsuoka , Kazuyuki Narisawa , Ryo Yoshinaka , Hideo Bannai , Shunsuke Inenaga , Ayumi Shinohara

Considering the optimal alignment of two i.i.d. random sequences of length $n$, we show that when the scoring function is chosen randomly, almost surely the empirical distribution of aligned letter pairs in all optimal alignments converges…

Probability · Mathematics 2012-11-26 Raphael Hauser , Heinrich Matzinger

The longest common subsequence (LCS) is a fundamental problem in string processing which has numerous algorithmic studies, extensions, and applications. A sequence $u_1, \ldots, u_f$ of $f$ strings s said to be an ($f$-)segmentation of a…

Data Structures and Algorithms · Computer Science 2025-02-27 Yuki Yonemoto , Takuya Mieno , Shunsuke Inenaga , Ryo Yoshinaka , Ayumi Shinohara

We consider two independent binary i.i.d. random strings $X$ and $Y$ of equal length $n$ and the optimal alignments according to a symmetric scoring functions only. We decompose the space of scoring functions into five components. Two of…

Probability · Mathematics 2017-08-02 Jun Tao Duan , Heinrich Matzinger , Ionel Popescu

We investigate the order of the variance of the optimal alignments score of two independent iid binary random words having the same length. The letters are equiprobable, but the scoring function is such that one letter has a larger score…

Probability · Mathematics 2016-06-17 Christian Houdré , Heinrich Matzinger

We investigate the variance of the length of the longest common subsequences of two independent random words of size $n$, where the letters of one word are i.i.d. uniformly drawn from $\{\alpha_1, \alpha_2, \cdots, \alpha_m\}$, while the…

Probability · Mathematics 2018-12-27 Christian Houdré , Qingqing Liu

In the Shortest Common Superstring problem (SCS), one needs to find the shortest superstring for a set of strings. While SCS is NP-hard and MAX-SNP-hard, the Greedy Algorithm "choose two strings with the largest overlap; merge them; repeat"…

Data Structures and Algorithms · Computer Science 2021-02-11 Maksim Nikolaev

Maximal Common Subsequences (MCSs) between two strings X and Y are subsequences of both X and Y that are maximal under inclusion. MCSs relax and generalize the well known and widely used concept of Longest Common Subsequences (LCSs), which…

Data Structures and Algorithms · Computer Science 2023-07-26 Alessio Conte , Roberto Grossi , Giulia Punzi , Takeaki Uno

This note provides very simple, efficient algorithms for computing the number of distinct longest common subsequences of two input strings and for computing the number of LCS embeddings.

Data Structures and Algorithms · Computer Science 2007-05-23 Ronald I. Greenberg

Longest common subsequence ($\mathsf{LCS}$) is a classic and central problem in combinatorial optimization. While $\mathsf{LCS}$ admits a quadratic time solution, recent evidence suggests that solving the problem may be impossible in truly…

Data Structures and Algorithms · Computer Science 2021-11-23 Aviad Rubinstein , Saeed Seddighin , Zhao Song , Xiaorui Sun

In this paper we define a new problem, motivated by computational biology, $LCSk$ aiming at finding the maximal number of $k$ length $substrings$, matching in both input strings while preserving their order of appearance. The traditional…

Data Structures and Algorithms · Computer Science 2014-02-11 Gary Benson , Avivit Levy , Riva Shalom

Calculating the length of a longest common subsequence (LCS) of two strings $A$ and $B$ of length $n$ and $m$ is a classic research topic, with many worst-case oriented results known. We present two algorithms for LCS length calculation…

Data Structures and Algorithms · Computer Science 2014-05-22 Szymon Grabowski

The Longest Common Subsequence (LCS) of two strings is a fundamental string similarity measure with a classical dynamic programming solution taking quadratic time. Despite significant efforts, little progress was made in improving the…

Data Structures and Algorithms · Computer Science 2021-12-17 Negev Shekel Nosatzki

In the minimum common string partition (MCSP) problem two related input strings are given. "Related" refers to the property that both strings consist of the same set of letters appearing the same number of times in each of the two strings.…

Data Structures and Algorithms · Computer Science 2017-02-02 Christian Blum , Günther R. Raidl

We define multi-block interleaved codes as codes that allow reading information from either a small sub-block or from a larger full block. The former offers faster access, while the latter provides better reliability. We specify the…

Information Theory · Computer Science 2017-01-26 Yuval Cassuto , Evyatar Hemo , Sven Puchinger , Martin Bossert

We consider string matching with variable length gaps. Given a string $T$ and a pattern $P$ consisting of strings separated by variable length gaps (arbitrary strings of length in a specified range), the problem is to find all ending…

Data Structures and Algorithms · Computer Science 2011-10-14 Philip Bille , Inge Li Goertz , Hjalte Wedel Vildhøj , David Kofoed Wind

The problem of the fluctuation of the Longest Common Subsequence (LCS) of two i.i.d. sequences of length $n>0$ has been open for decades. There exist contradicting conjectures on the topic. Chvatal and Sankoff conjectured in 1975 that…

Probability · Mathematics 2010-11-15 Heinrich Matzinger , Felipe Torres

We investigate the longest common substring problem for encoded sequences and its asymptotic behaviour. The main result is a strong law of large numbers for a re-scaled version of this quantity, which presents an explicit relation with the…

Probability · Mathematics 2019-12-12 Adriana Coutinho , Rodrigo Lambert , Jérôme Rousseau

The fundamental question considered in algorithms on strings is that of indexing, that is, preprocessing a given string for specific queries. By now we have a number of efficient solutions for this problem when the queries ask for an exact…

Data Structures and Algorithms · Computer Science 2023-04-04 Paweł Gawrychowski , Garance Gourdel , Tatiana Starikovskaya , Teresa Anna Steiner

Let $\Sigma$ be an alphabet. For two strings $X$, $Y$, and a constrained string $P$ over the alphabet $\Sigma$, the constrained longest common subsequence and substring problem for two strings $X$ and $Y$ with respect to $P$ is to find a…

Data Structures and Algorithms · Computer Science 2023-08-04 R. Li , J. Deka , K. Deka , D. Li