Horspool, R. (1980). Practical fast searching in strings. Software---Practice and Experience, Vol. 10, pp. 501--506. This article was processed using the L  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Boyer Moore heuristics for multiple patterns and achieved performance significantly better than Aho Corasick or Commentz Walter for natural language texts [35] Many of these algorithms have increasingly good, but complex algorithms for skipping. As evidenced by Horspool s variant of Boyer Moore [16], simpler search algorithms can often perform better than algorithms which skip more characters per comparison, but require much more work per skip. Horspool uses only the bad character heuristic of Boyer and Moore and not the good su#x heuristic, without loss of average case performance. In this ....

R. Nigel Horspool, "Practical fast searching in strings," Software Practice and and Experience, vol. 10, no. 6, pp. 501--506, 1980.

....of or m, if the input string T is packed such that each symbols takes just dlog 2 e bits. Therefore, the method gives a true asymptotic, not a constant factor, speed up. Super alphabet methods have appeared before, and the idea was mentioned already in [11, 5] In [2] the bmh algorithm [9] was modi ed to use a super alphabet. This e ectively reduced the probability of match of two random characters, thus yielding longer shifts. Similar methods were presented in [17, 16] These techniques di er from the one taken here; we apply our method to a sux automaton [7] often called bdm, ....

R. N. Horspool. Practical fast searching in strings. Softw. Pract. Exp., 10(6):501{ 506, 1980.

....we tested also with such an extreme text as a 1000000 and pattern a 1000 , where searching was 19 times faster with LCP values in suOEx array. Finally, we compared CSA with suOEx array and sequential search. In sequential search, we used the implementation of Boyer Moore Horspool algorithm [7] from [4] with a simple modication to report all the matches) We used the algorithm of Larsson and Sadakane [10] to construct suOEx arrays. To guarantee a fair comparison, we represented suOEx arrays in ndlog ne bits instead of the usual 4n bytes implementation. We did not use LCP values in ....

R. N. Horspool, Practical fast searching in strings, Soft. Pract. and Exp., 10, 1980, pp. 501-506.

....its eciency by scanning, at each attempt, the characters of the window from right to left, recognizing some sux of the pattern, performing a shift and thus, in most cases, avoiding to look at all the characters of the text. Several experiments on exact string matching have already been reported ([3], 4] 5] 6] 7] 8] 9] and [10] In this article we compare the performances of three di erent implementations of the Boyer Moore algorithm, namely the Tuned Boyer Moore algorithm [7] the Quick Search algorithm [11] and the Berry Ravindran algorithm [9] with algorithms using trees or ....

R. N. Horspool. Practical fast searching in strings. Softw. Pract. Exp., 10(6):501-506, 1980.

....i in the text. It searches backwards a suffix of t 1 : t i which is also a suffix of the pattern. If the suffix is the whole pattern a match is reported. Then the window is shifted to the next occurrence of the suffix in the pattern. This algorithm leads to several variations, like Hoorspool [15] and Sunday [25] This latest one is considered as the fastest string matching algorithm in practice. A large part of the research in efficient algorithms for string matching can be regarded as looking for automata which are efficient in some sense. For instance, KMP is simply a deterministic ....

R. N. Horspool. Practical fast searching in strings. Softw. Pract. Exp., 10:501--506, 1980.

....text pattern a 6= b i 6 j a b match match match oe match shift Fig. 2. Match heuristic. The occurrence shift depends on the alphabet Sigma. It causes the mismatching symbol of the text to be aligned with the closest matching symbol of the pattern (see Figure 3) Horspool [17] improved this heuristic by aligning the rightmost inspected text character while Sunday [22] suggested to use the first non inspected text character to the right. The shift function depends only on the pattern and the alphabet. Thus it can be precomputed, during the so called preprocessing phase. ....

R.N. Horspool, 'Practical fast searching in strings', Software-Practice and Experience 10, 501-506 (1980).

.... in terms of the number of symbol comparisons are the algorithm of Apostolico and Giancarlo (1986) Turbo BM algorithm by Crochemore et al..ii (1992) the two previous algorithms are analyzed in [Lecroq, 1995] and the algorithm of Colussi ( Colussi, 1994] The Horspool algorithm is from [Horspool, 1980]. The paper contains practical aspects of string matching that are developed in [Hume and Sunday, 1993] The optimal bound on the expected time complexity of string matching is O( log m m n) see [Knuth, Morris, and Pratt, 1977] and the paper of Yao (1980) String matching can be solved by ....

Horspool, R.N. 1980. Practical fast searching in strings. Software -- Practice and Experience.

....exist to solve this problem. One of the most famous, and the first having linear worst case behavior, is Knuth Morris Pratt (KMP) 14] A second algorithm, as famous as KMP, which allows to skip characters, is BoyerMoore (BM) 6] This algorithm leads to several variations, like Hoorspool [12] and Sunday [20] forming the fastest known string matching algorithms. A large part of the research in efficient algorithms for string matching can be regarded as looking for automata which are efficient in some sense. For instance, KMP is simply a deterministic automaton that searches the ....

R. N. Horspool. Practical fast searching in strings. Softw. Pract. Exp., 10:501--506, 1980.

....matching (Chapter 4) All of these algorithms, both the previous work and the new results, are placed in an alignment graph dynamic programming framework which simplifies much of the algorithms complexity and links these results back to the simple edit distance and LCS solutions. 10 [KMP77] Hor80] Sun90] HS91] Rai92] Smi92] Keyword Matching SC w Extended Operations Sequence Scoring Gap Penalty SC w Reg. Exp. Pat. Matching Approximate Reg. Exp. Pat. Matching [CHM93] CPM92] Epp90] MM89b] GP89] GG89] AE86a] Wat84a] Tay84] Got82] MM88b] Wil88] k Differences Problem ....

R. N. Horspool. "Practical Fast Searching in Strings." Software - Pract. Exper. 10 (1980), 501--506.

....of looking for all pairs of p matches in the input, the overhead involved in building p suffix trees suggests looking for other approaches to parameterized pattern matching. For strings, the Boyer Moore (BM) algorithm [BM77] and its variants are the algorithms of choice for pattern matching [Hor80, HS91, Sun90] Most of these algorithms share the common characteristic of comparing pattern with text from right to left, and when a mismatch occurs, using some form of shift rule to determine how far to the right to shift the pattern before comparing it again with the text. However, the form of ....

R. Nigel Horspool. Practical fast searching in strings. Soft. Pract. and Exp., 10:501--506, 1980.

....algorithm is substantially faster than the Aho Corasick algorithm in practice. Hume [Hu91] designed a tool called gre based on this algorithm, and version 2.0 of fgrep by the GNU project [Ha93] is using it. Baeza Yates [Ba89] also gave an algorithm that combines the Boyer Moore Horspool algorithm [Ho80] (which is a slight variation of the classical Boyer Moore algorithm) with the Aho Corasick algorithm. We present a different approach that also uses the ideas of Boyer and Moore. Our algorithm is quite simple, and the main engine of it is given later in the paper. An earlier version of this ....

Horspool, N., "Practical Fast Searching in Strings," Software --- Practice and Experience, 10 (1980).

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Horspool, R. (1980). Practical fast searching in strings. Software---Practice and Experience, Vol. 10, pp. 501--506. This article was processed using the L

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R. N. Horspool, `Practical fast searching in strings', Software---Practice and Experience, 10, 501--506 (1980).

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Horspool, R. (1980). Practical fast searching in strings. Software---Practice and Experience, Vol. 10, pp. 501--506. This article was processed using the L A T E X 2 " macro package with CUP CS class

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R.N. Horspool, Practical Fast Searching in Strings, Software, Practice and Experience, 10(6), 1980, pp 501--506.

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R. Nigel Horspool. Practical fast searching in strings. Software|Practice and Experience, 10(6):501-506, 1980.

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N. Horspool, `Practical fast searching in strings', Software---Practice and Experience, 10, 501--506 (1980).

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R. N. Horspool, `Practical fast searching in strings,' Software---Practice and Experience 10, (3), 501--506 ( 1980).

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