Fast Pattern Matching in Strings

Knuth, Donald E.; Morris, James H.; Pratt, Vaughan R.

doi:10.1137/0206024

Cited by 2,293 publications

(1,173 citation statements)

References 16 publications

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“…In this section, we compare the space requirement and the throughput performance of our proposed generalized scheme, the NR scheme, the Kida scheme, and the one that performs decompression followed by pattern searching with the Knuth-Morris-Pratt (KMP) algorithm [9].…”

Section: Resultsmentioning

confidence: 99%

An efficient pattern matching scheme in LZW compressed sequences

Lee

Huang

2008

Security Comm Networks

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SummaryCompressed pattern matching (CPM) is an emerging research field addressing the problem: given a compressed sequence and a pattern, process the sequence with minimal (or no) decompression to find the pattern occurrence(s) in the uncompressed sequence. It can be applied to detect malwares and confidential information leakage in compressed files directly. In this paper, we report our work of CPM in Lempel-Ziv-Welch (LZW) compressed sequences. We propose an efficient bitmap-based realization of the Amir-Benson-Farach algorithm. We also generalize the algorithm to find all pattern occurrences and report their absolute positions in the uncompressed sequence. Experiments are conducted to test the space requirements of our proposed generalization and two related CPM schemes which can also be realized with bitmaps. Results show that our proposed generalization requires the least amount of storage for moderate and long patterns. We also conduct experiments to compare the throughput performance of our proposed generalization with these two related CPM schemes and the decompress-then-search scheme. Results show that our proposed generalization outperforms the decompress-then-search scheme significantly. When scanning a file with pattern occurrences, our proposed generalization performs slightly better than the two related CPM schemes. The difference is significant when scanning a file with no pattern occurrence.

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Section: Resultsmentioning

confidence: 99%

An efficient pattern matching scheme in LZW compressed sequences

Lee

Huang

2008

Security Comm Networks

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“…This can be verified in linear time with any classical pattern matching algorithm, e.g. [14]. The second requirement is that there is a scale r for which P scales properly to match at the appropriate location in T .…”

Section: A Local Verification Algorithmmentioning

confidence: 99%

“…The original classical string matching problem [10,14] was motivated by text searching. Wide advances in technology, e.g.…”

Section: Introductionmentioning

confidence: 99%

Efficient One Dimensional Real Scaled Matching

Amir

Butman

Lewenstein

et al. 2004

String Processing and Information Retrieval

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Real Scaled Matching is the problem of finding all locations in the text where the pattern, proportionally enlarged according to an arbitrary real-sized scale, appears. Real scaled matching is an important problem that was originally inspired by Computer Vision.In this paper, we present a new, more precise and realistic, definition for one dimensional real scaled matching, and an efficient algorithm for solving this problem. For a text of length n and a pattern of length m, the algorithm runs in time O(n log m + √ nm 3/2 √ log m).

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“…Failure transitions make their first appearance in an article on pattern matching by Knuth et al (1974Knuth et al ( , 1977. The authors give a linear-time algorithm for finding all occurrences of a pattern string within a text string.…”

Section: Related Workmentioning

confidence: 99%

Compression of finite-state automata through failure transitions

Björklund

Zechner

2014

Theoretical Computer Science

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Compression of finite AbstractSeveral linear-time algorithms for automata-based pattern matching rely on failure transitions for efficient back-tracking. Like epsilon transitions, failure transition do not consume input symbols, but unlike them, they may only be taken when no other transition is applicable. At a semantic level, this conveniently models catch-all clauses and allows for compact language representation. This work investigates the transition-reduction problem for deterministic finite-state automata (DFA). The input is a DFA A and an integer k. The question is whether k or more transitions can be saved by replacing regular transitions with failure transitions. We show that while the problem is NP -complete, there are approximation techniques and heuristics that mitigate the computational complexity. We conclude by demonstrating the computational difficulty of two related minimisation problems, thereby cancelling the ongoing search for efficient algorithms.

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Fast Pattern Matching in Strings

Cited by 2,293 publications

References 16 publications

An efficient pattern matching scheme in LZW compressed sequences

An efficient pattern matching scheme in LZW compressed sequences

Efficient One Dimensional Real Scaled Matching

Compression of finite-state automata through failure transitions

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