Manoochehr Azmoodeh · 1990
In this chapter we introduce the abstract data type string and describe some basic string-processing operations. The purpose here is not to give a full exposition of special-purpose string-handling facilities, but instead to concentrate on string searching and emphasise the role of algorithm design. The hope is that these algorithms will further elicit the algorithm design paradigms discussed in chapter 8. More specialised string-processing systems and tools such as text editors and specialised string-manipulation languages such as SNOBOL offer powerful facilities. The interested reader is referred to the bibliographic notes at the end of the chapter.
Cited by 1
2008
Abstract — We propose a new string searching procedure inspired by the Boyer–Moore algorithm. The two key ideas of our improvement are to keep track of all the previously matched characters within the current alignment and not to move the reading position unconditionally to the end of the pattern when a mismatch occurs. The result is an algorithm with increased average shift amounts and a guarantee that any character of the text is read at most once. The algorithm performs especially well when the alphabet size is small. We also discuss and test variants of the original idea aimed at practical implementations. Index Terms — string searching, Boyer-Moore algorithm, pattern matching, finite automaton
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Tatsuya Akutsu · 1995
This paper presents an O(mn log n) time algorithm for an approximate string matching problem, in which a pattern string may contain variable length don't care characters. This problem is important for searching DNA sequences or amino acid sequences.
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Shuai Xun-bo, Xiangguang Zhou · Procedia Environmental Sciences · 2011
Dual operator and inverse operator are defined as two new genetic operators respectively in this paper. Then a genetic algorithm based on inverse and dual combination operator was designed to overcome the defect of genetic algorithm in local searching, which combined with uniform crossover. The genetic algorithm is proved to be convergent. Experiments show that it has better searching performance and it has good reference to string-coded genetic algorithm in solving nonlinear optimization problems.
Cited by 13Open access
Latorre Vilca, Omar · LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) · 2020
In this paper we address CLOSEST STRING problem that arises in web searching, coding theory and computational molecular biology. To solve it is to find a string that minimizes the maximum Hamming distance from a given set of strings. CLOSEST STRING is an NP-hard problem. This paper proposes two linear-time algorithms, one for the general case, a kernelization algorithm, and the other for three-strings, a linear-time algorithm called Minimization First Algorithm (MFA). A formal proof of the correctness and the computational complexity of the proposed algorithms are given.
Cited by 0Open access
Faro S., Marino F. P., Pavone A. · Nova Science Publishers (Nova Science Publishers, Inc.) · 2021
Sampled string matching is an efficient approach to the string matching problem introduced in order to overcome the prohibitive space requirements of indexed matching, on the one hand, and drastically re- duce searching time for the online solutions, on the other hand. Known solutions to sampled string matching are able to speed up the searching up to 9 times while using less than 11% of the text size. However, they appear to work efficiently only in the case of natural language texts or, in general, when searching on input sequences over large alphabets. \nIn this paper we extend sampled-string matching to the case of small al- phabets obtaining a new efficient solution which turns out to be feasible also for searching biological data like genome or protein sequences. Our solution extends a recent approach called Character Distance Sampling by using condensed characters in order to enlarge the size of the alpha- bet and speed up the searching process. From our experimental results it turns out that our solution significantly reduces the searching time when compared against previous sampled string matching algorithms. In particular on biological data it leads to reduce the space consumption up to 80% and to speed up the searching up to 96%, thus improving the standard online string matching algorithm up to 99.6% using less than 1% of the original text size.
Cited by 0Open access
Dipendra Gurung, Udit Kr. Chakraborty, Pratikshya Sharma · International Journal of Information Technology and Computer Science · 2017
Due to the huge surge of digital information and the task of mining valuable information from huge amount of data, text processing tasks like string search has gained importance. Earlier techniques for text processing relied on following some predetermined sequence of steps or some hard coded rules. However, these techniques might soon prove to be inefficient as the amount of data generated by modern computer systems in increasing more and more. One solution to this problem lies in the development of intelligent algorithms that incorporate a certain degree of intelligence and unlike traditional algorithm are able to cope up with changing scenarios. This paper presents a string searching algorithm that incorporates a certain degree of intelligence to search for a string in a text. In the search of a string, the algorithm relies on a chance process and a certain probability at each step. An analysis of the algorithm based on the approach suggested by A. A. Markov is also presented in the paper. The expected number of average comparisons required for searching a string in a text is computed. Based on the varieties of applications that are coming up in the area of text processing and the related fields, this new algorithm aims to find its use.
Cited by 5Open access
Mustafa Abdul Sahib Naser, Nur’Aini Abdul Rashid, Mohammed Faiz Aboalmaaly · International Journal of Computer Theory and Engineering · 2012
The string matching problem occupies a corner stone in many computer science fields because of the fundamental role it plays in various computer applications. Thus, several string matching algorithms have been produced and applied in most operating systems, information retrieval, editors, internet searching engines, firewall interception and searching nucleotide or amino acid sequence patterns in genome and protein sequence databases. Several important factors are considered during the matching process such as number of character comparisons, number of attempts and the consumed time. This research proposes a hybrid exact string matching algorithm by combining the good properties of the Quick Search and the Skip Search algorithms to demonstrate and devise a better method to solve the string matching problem with higher speed and lower cost. The hybrid algorithm was tested using different types of standard data. The hybrid algorithm provides efficient results and reliability compared with the original algorithms in terms of number of character comparisons and number of attempts when the hybrid algorithm applied with different pattern lengths. Additionally, the hybrid algorithm produced better quality in performance through providing less time complexity for the worst and best cases comparing with other hybrid algorithms.
Cited by 13
Daniar Heri Kurniawan, Rinaldi Munir · 2015
Searching process performance is very important in this modern world that consists of various advanced technology. String matching algorithm is one of the most commonly applied algorithms for searching. String that contains sequences of character is the simplest representation of any complex data in our real life, such as search engine database, finger print minutiae, or DNA sequence. The current most famous string algorithms are Knuth-Morris-Pratt (KMP) algorithm and Boyer-Moore (BM) algorithm. Boyer-Moore algorithm and KMP algorithm are not efficient in some cases. We introduced a new variation of string matching algorithm based on Logical-Indexing (LI), which is more efficient than those algorithms. Logical-Indexing algorithm implements a new function or method and defines different jumping rules compared to others. The indexes of texts and patterns are used to reduce the number of comparisons. Index enables us to analyze the condition of comparison without directly comparing each character in the pattern. Theoretically, we have proven that Logical-Indexing algorithm can skip more characters than KMP and BM algorithm by analyzing KMP's and BM's weaknesses then giving the better solution that are implemented in LI. Furthermore, experiments conducted on various combinations of pattern matching cases also demonstrate that the average number of LI's direct comparisons is smaller than KMP's and BM's algorithm.
Cited by 3
Ovidiu Domşa, Emilian Ceuca, Mircea Rasteiu · 2013
Abstract. Searching algorithms in data structures are the most common problems in the research and development of structures like string, heap or graph. We propose to solve a NP complete problem of searching in a large graph. The algorithm finds a substructure with certain properties in real time. We propose to find a tree with maximal terminal nodes using a heuristic algorithm in 2-approximation method. 1
Cited by 0
Chan Chung Hoong, Mohamed Ariff Ameedeen · Advanced Science Letters · 2017
After a deep view on few fast searching algorithm as Boyer-Moore algorithm, Boyer-Moore Horspool algorithm, Brute-Force Algorithm, Knuth-Morris-Pratt algorithm and Rabin-Karp algorithm, this research paper chooses Boyer-Moore Horspool algorithm to used in the content management system in term of data Fast Searching. An enormous amount of data stored in content management system as few big module as product data, slider data, personal information data, company information data, account data and another kind of data may refer to the different type of content management system and developer set. However, search specific data from all the above data type that mention, memory, and time consumed is used up. Therefore, from this paper, Boyer-Moore Horspool Algorithm is being chosen to use in content management system after comparing a few searching algorithm in research which will state in this article. The aim of this paper is to analysis few searching algorithm and choose the most suit algorithm that giving the fastest searching time consumed while searching long string data.
Cited by 2
Dmitry V. Pashchenko, Dmitry A. Trokoz, А. И. Мартышкин et al. · Bulletin of Electrical Engineering and Informatics · 2020
The paper proposed an algorithm which purpose is searching for a substring of characters in a string. Principle of its operation is based on the theory of non-deterministic finite automata and vector-character architecture. It is able to provide the linear computational complexity of searching for a substring depending on the length of the searched string measured in the number of operations with hyperdimensional vectors when repeatedly searching for different strings in a target line. None of the existing algorithms has such a low level of computational complexity. The disadvantages of the proposed algorithm are the fact that the existing hardware implementations of computing systems for performing operations with hyperdimensional vectors require a large number of machine instructions, which reduces the gain from this algorithm. Despite this, in the future, it is possible to create a hardware implementation that can ensure the execution of operations with hyperdimensional vectors in one cycle, which will allow the proposed algorithm to be applied in practice.
Cited by 15Open access
Chan, Chung Hoong, M. A., Ameedeen · UMP Institutional Repository (Universiti Malaysia Pahang) · 2016
After a deep view on few fast searching algorithm as Boyer-Moore algorithm, Boyer-Moore Horspool algorithm, Brute-Force Algorithm, Knuth-Morris-Pratt algorithm and Rabin-Karp algorithm, this research paper chooses Boyer-Moore Horspool algorithm to used in the content management system in term of data Fast Searching. An enormous amount of data stored in content management system as few big module as product data, slider data, personal information data, company information data, account data and another kind of data may refer to the different type of content management system and developer set. However, search specific data from all the above data type that mention, memory, and time consumed is used up. Therefore, from this paper, Boyer-Moore Horspool Algorithm is being chosen to use in content management system after comparing a few searching algorithm in research which will state in this article. The aim of this paper is to analysis few searching algorithm and choose the most suit algorithm that giving the fastest searching time consumed while searching long string data.
Cited by 0
Christian Charras, Thierry Lecroq, Joseph Daniel Pehoushek · 2007
We are interested in the exact string matching problem which consists of searching for all the occurrences of a pattern of length m in a text of length n. Both the pattern and the text are built over an alphabet \\Sigma of size oe. We present three versions of an exact string matching algorithm. They use a new shifting technique. The first version is straightforward and easy to implement. The second version is linear in the worst case, an improvement over the first. The main result is the third algorithm. It is very fast in practice for small alphabet and long patterns. Asymptotically, it performs O(log oe m(m + n=(m \\Gamma log oe m))) inspections of text symbols in the average case. This compares favorably with many other string searching algorithms.
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Christian Charras, Thierry Lecroq, Joseph Daniel Pehoushek · 1998
We are interested in the exact string matching problem which consists of searching for all the occurrences of a pattern of length m in a text of length n. Both the pattern and the text are built over an alphabet \\Sigma of size oe. We present three versions of an exact string matching algorithm. They use a new shifting technique. The first version is straightforward and easy to implement. The second version is linear in the worst case, an improvement over the first. The main result is the third algorithm. It is very fast in practice for small alphabet and long patterns. Asymptotically, it performs O(log oe m(m + n=(m \\Gamma log oe m))) inspections of text symbols in the average case. This compares favorably with many other string searching algorithms.
Cited by 0
Guoyong Shi, Hitoshi Iima, Nobuo Sannomiya · 2002
A new encoding scheme in genetic algorithms is proposed by using an ordering string for the classic job shop scheduling problem. A genetic algorithm is designed for searching the semi-active schedule space, which is encoded by the string space. A new crossover, set-partition crossover is introduced in accompanying the genetic searching. An associated selection strategy and a production structure are properly established for this fashion of encoding. This encoding scheme naturally overcomes the infeasibility problem in genetic iterations. Experiments show that the proposed genetic algorithm is effective, and optimal solutions are attainable in some probability for Fisher and Thompson problems with definite hardness.
Cited by 42
Chouvalit Khancome · WSEAS TRANSACTIONS ON COMPUTERS · 2023
This research article introduces a new string-matching algorithm that utilizes the multi-character inverted lists structure, implemented using a perfect hashing method. The new solution processes the pattern input string in a single pass. In the searching phase, the algorithm takes a linear time complexity. This approach demonstrates efficient and rapid performance in practical experiments when a binary character set is used. It also handles fewer characters and shorter lengths, even when the pattern length is increased. In some cases, this algorithm exhibits superior text search performance compared to other algorithms. It has been observed that this superiority is particularly evident when searching for smaller amounts of text. This algorithm can be explored more quickly, especially when the search factor is between 0.25 to 0.75 times the length of the pattern, approaching the performance of the traditional algorithm.
Cited by 2Open access
2008
Abstract—A new algorithm called Character-Comparison to Character-Access (CCCA) is developed to test the effect of both: 1) converting character-comparison and number-comparison into character-access and 2) the starting point of checking on the performance of the checking operation in string searching. An experiment is performed; the results are compared with five algorithms, namely, Naive, BM, Inf_Suf_Pref, Raita, and Circle. With the CCCA algorithm, the results suggest that the evaluation criteria of the average number of comparisons are improved up to 74.0%. Furthermore, the results suggest that the clock time required by the other algorithms is improved in range from 28 % to 68 % by the new CCCA algorithm Keywords—Pattern matching, string searching, charactercomparison, character-access, and checking. I.
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N.N. Zaitseva, Tatiana Moiseeva · Models systems networks in economics technology nature and society · 2024
Background. The generally accepted approach to management in organizational systems today differs in that participants in problematic situations (PrS) are excluded from the processes of their solution. Complementing the traditional approach to management with the ability to solve PrS by the actors themselves makes it possible to enrich decision-making processes through the use of volitional and intellectual resources of subjects. For information support of actors, a decision support system (DSS) is being developed, the design of which faced the task of choosing methods for searching and comparing various objects in the process of intersubjective management of PrS solution. The purpose of the study is to analyze and select methods for searching and comparing various objects in the database, knowledge base, and library of DSS precedents, which can be used in the development of algorithms for supporting and making decisions by actors building personal ontologies of the DSS as a result of communication on the DSS site. Materials and methods. The materials are the main provisions of the theory of intersubjective management of problematic situations solution. Methods of comparison and search in the database and knowledge base of similar objects – algorithms for fuzzy string comparison and methods for finding substrings in a string, as well as management theory, system analysis, decision theory, knowledge engineering. Results. A review of methods for searching and comparing data is carried out, with an emphasis on methods applicable to subject-to-subject (intersubjective) management of the PrS solution. Among the well-known algorithms, four of the most popular fuzzy string comparison algorithms are highlighted: Hamming algorithm, Levenstein editorial distance (algorithm), Damerau–Levenstein editorial distance (algorithm) and distance (algorithm) Jaro-Winkler. Among the search algorithms applicable to one–dimensional string arrays of data, the following are highlighted and considered: the simple search algorithm (linear algorithm), the Robin–Karp algorithm and the Knuth–Morris-Pratt algorithm. Conclusions. It is proposed to use a linear algorithm as the most suitable for solving problems related, for example, to searching the library for use cases by the names of the PrS and keywords.
Cited by 0Open access
Sun Wu, Udi Manber · 1992
Searching for a pattern in a text file is a very common operation in many applications ranging from text editors and databases to applications in molecular biology. In many instances the pattern does not appear in the text exactly. Errors in the text or in the query can result from misspelling or from experimental errors (e.g., when the text is a DNA sequence). The use of such approximate pattern matching has been limited until now to specific applications. Most text editors and searching programs do not support searching with errors because of the complexity involved in implementing it. In this paper we describe a new tool, called agrep, for approximate pattern matching. Agrep is based on a new efficient and flexible algorithm for approximate string matching. Agrep is also competitive with other tools for exact string matching; it include many options that make searching more powerful and convenient. 1. Introduction The most common string-searching problem is to find all occurrences ...
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