T. Lecroq. Experimental results on string matching algorithms. Software Practice and Experience, 25(7):727--765, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... c 2 can be specified to avoid enumerating all the letters between (and including) c 1 and c 2 . Finally, the period ( represents any character. 2 The reverse factor search approach In this section we describe the general reverse factor search approach currently used for a single pattern [12, 9, 14] or multiple patterns [8, 15] The search is done using a window which has the length of the minimum word that we search (if we search a single word, we just take its length) We note this minimum length . We shift the window along the text, and for each position of the window, we search ....

T. Lecroq. Experimental results on string matching algorithms. Softw. Pract. Exp., 25(7):727--765, 1995.

....avoid the quadratic behavior when searching for all occurrences of the pattern. Among the most efficient 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 ....

Lecroq, T. 1995. Experimental results on string-matching algorithms. Software -- Practice and Experience. 25:727--765.

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Lecroq, T. 1995. Experimental results on string-matching algorithms. Software|Practice Exp. 25(7):727-765.

....is composed of 29:63 per cent of Adenine, 20:56 per cent of Cytosine, 22:95 per cent of Guanine and 26:86 per cent of Thymine. C code We used a program written in C. The alphabet is composed of 93 di erent characters. The text is composed of 140; 240 characters. The distribution can be found in [21]. Natural language We used Lewis Caroll s novel Alice s Adventures in Wonderland. The alphabet is composed of 70 di erent characters. The text is composed of 148; 188 characters. The distribution can be found in [21] Text character inspections For each run of the algorithms we counted the ....

....The text is composed of 140; 240 characters. The distribution can be found in [21] Natural language We used Lewis Caroll s novel Alice s Adventures in Wonderland. The alphabet is composed of 70 di erent characters. The text is composed of 148; 188 characters. The distribution can be found in [21]. Text character inspections For each run of the algorithms we counted the average number c of inspections for one text character. It means that we counted each time a text character is accessed, either to perform a comparison with a pattern character or to perform a shift or to compute a ....

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T. Lecroq. Experimental results on string matching algorithms. Softw. Pract. Exp., 25(7):727-765, 1995. 32

....an alphabet Sigma. Numerous algorithms have been designed to solve this problem (see [1] and [2] All these algorithms can be divided in two categories: the algorithms which assumed that the alphabet is bounded and the others. The faster algorithms in practice are of the former category (see [3]) because they use heuristics based on the alphabet. However they need to store a particular shift length for each symbol. When a short sequence of numbers has to be searched in a larger one or when a sequence of records has to be found in a flat file then the underlying alphabet is unbounded. ....

.... (BM) 5] and the Reverse Factor algorithm (RF) 6] and [7] and four for the bounded case (the Boyer Moore algorithm, the Horspool algorithm (HOR) 8] the Quick Search algorithm (QS) 9] and the Tuned Boyer Moore algorithm (TBM) 10] The five first algorithms have already been presented in [3]. We will only emphasize here on the improvement made, if any. We modified all the original algorithms to add a fast loop (ufast according to the terminology 2 of [10] which consists in checking if the rightmost symbol of the window leeds to a match before checking the remaining symbols of the ....

T. Lecroq. Experimental results on string matching algorithms. Software--Practice and Experience, 25(7):727--765, 1995.

....Case 1 : identical to Case 1) k suf [i] and suf [i] i 1. An occurrence of x is found at position j (see Figure 8) Case 2 : k suf [i] and suf [i] i. A mismatch occurs between characters y[j 1 i Gamma suf [i] and x[i Gamma suf [i] see Figure 9) Thus, as already mentioned in [8], the length of the shift is computed as in algorithm BM (i.e. using dd 0 [i Gamma suf [i] 1] and d[y[j 1 i Gamma suf [i] 7 i x x y j 0 j 1 k suf [i] 6= Figure 10: Case 3 , k suf [i] a mismatch occurs between y[j 1 i Gamma k] and x[i Gamma k] i x x y j 0 j 1 k ....

T. Lecroq, Experimental results on string matching algorithms, Software--Practice & Experience 27(5) (1995) 727--765.

....Case 1 : identical to Case 1) k suf [i] and suf [i] i 1. An occurrence of x is found at position j (see Figure 8) Case 2 : k suf [i] and suf [i] i. A mismatch occurs between characters y[j 1 i Gamma suf [i] and x[i Gamma suf [i] see Figure 9) Thus, as already mentioned in [8], the length of the shift is computed as in algorithm BM (i.e. using dd 0 [i Gamma suf [i] 1] and d[y[j 1 i Gamma suf [i] Case 3 : k suf [i] A mismatch occurs between characters y[j 1 i Gamma k] and x[i Gamma k] see Figure 10) Thus a shift can be performed using dd 0 [i ....

T. Lecroq, Experimental results on string matching algorithms, Software-- Practice & Experience 27(5) (1995) 727--765.

....y[j1 i Gamma k] and x[i Gamma k] i x x y j0 j1 k suf [i] 6= 6= c b a Fig. 11. Case 4 , k = suf [i] a 6= b and b 6= c. Case 2 : k suf [i] and suf [i] i. A mismatch occurs between characters y[j 1 i Gamma suf [i] and x[i Gamma suf [i] see Figure 9) Thus, as already mentioned in [8], the length of the shift is computed as in algorithm BM (i.e. using dd 0 [i Gamma suf [i] 1] and d[y[j 1 i Gamma suf [i] Case 3 : k suf [i] A mismatch occurs between characters y[j 1 i Gamma k] and x[i Gamma k] see Figure 10) Thus a shift can be performed using dd 0 [i ....

T. Lecroq, Experimental results on string matching algorithms, Software-- Practice & Experience 27(5) (1995) 727--765.

....over an alphabet Sigma. Numerous algorithms have been designed to solve this problem (see [1] and [2] All these algorithms can be divided in two categories: the algorithms that assumed that the alphabet is finite and the others. The faster algorithms in practice are of the former category (see [3]) because they use heuristics based on the alphabet. However they need to store a particular value for each symbol. No study had been done in practice when searching over a potentially infinite alphabet. Obviously this case can reduced to a search over a finite alphabet (namely characters) ....

....the symbols of y[n; n m Gamma 1] to x[m Gamma 1] And as in the Boyer Moore algorithm, when one of this symbol is matched, the test j n is postponed before reporting a full match. The Reverse Factor algorithm has a quadratic worst case time complexity but it performs very well in practice (see [3]) Finite alphabet Now we consider each symbol of the alphabet Sigma as a sequence of p bytes. Searching for a word x of length m in a text y of length n over an infinite alphabet reduces in searching for a word x 0 of length m 0 = pm in a text y 0 of length n 0 = pn over a finite ....

T. Lecroq. Experimental results on string matching algorithms. Software--Practice and Experience, 25(7):727--765, 1995.

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T. Lecroq. Experimental results on string matching algorithms. Software Practice and Experience, 25(7):727--765, 1995.

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:323--350. Lecroq, T. 1995. Experimental results on string-matching algorithms. Software - Practice & Experience

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