Abstract
A run is an inclusion maximal occurrence in a string (as a subinterval) of a repetition v with a period p such that 2p ≤ |v|. The exponent of a run is defined as |v|/p and is ≥ 2. We show new bounds on the maximal sum of exponents of runs in a string of length n. Our upper bound of 4.1 n is better than the best previously known proven bound of 5.6 n by Crochemore & Ilie (2008). The lower bound of 2.035 n, obtained using a family of binary words, contradicts the conjecture of Kolpakov & Kucherov (1999) that the maximal sum of exponents of runs in a string of length n is smaller than 2n.
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References
Berstel, J., Karhumaki, J.: Combinatorics on words: a tutorial. Bulletin of the EATCS 79, 178–228 (2003)
Crochemore, M., Ilie, L.: Analysis of maximal repetitions in strings. In: Kucera, L., Kucera, A. (eds.) MFCS 2007. LNCS, vol. 4708, pp. 465–476. Springer, Heidelberg (2007)
Crochemore, M., Ilie, L.: Maximal repetitions in strings. J. Comput. Syst. Sci. 74(5), 796–807 (2008)
Crochemore, M., Ilie, L., Rytter, W.: Repetitions in strings: Algorithms and combinatorics. Theor. Comput. Sci. 410(50), 5227–5235 (2009)
Crochemore, M., Ilie, L., Tinta, L.: Towards a solution to the ”runs” conjecture. In: Ferragina, P., Landau, G.M. (eds.) CPM 2008. LNCS, vol. 5029, pp. 290–302. Springer, Heidelberg (2008)
Crochemore, M., Iliopoulos, C.S., Kubica, M., Radoszewski, J., Rytter, W., Walen, T.: On the maximal number of cubic runs in a string. In: Dediu, A.H., Fernau, H., Martín-Vide, C. (eds.) LATA 2010. LNCS, vol. 6031, pp. 227–238. Springer, Heidelberg (2010)
Franek, F., Yang, Q.: An asymptotic lower bound for the maximal number of runs in a string. Int. J. Found. Comput. Sci. 19(1), 195–203 (2008)
Giraud, M.: Not so many runs in strings. In: Martín-Vide, C., Otto, F., Fernau, H. (eds.) LATA 2008. LNCS, vol. 5196, pp. 232–239. Springer, Heidelberg (2008)
Gusfield, D., Stoye, J.: Simple and flexible detection of contiguous repeats using a suffix tree (preliminary version). In: Farach-Colton, M. (ed.) CPM 1998. LNCS, vol. 1448, pp. 140–152. Springer, Heidelberg (1998)
Kolpakov, R.M., Kucherov, G.: Finding maximal repetitions in a word in linear time. In: Proceedings of the 40th Symposium on Foundations of Computer Science, pp. 596–604 (1999)
Kolpakov, R.M., Kucherov, G.: On maximal repetitions in words. J. of Discr. Alg. 1, 159–186 (1999)
Kolpakov, R.M., Kucherov, G.: On the sum of exponents of maximal repetitions in a word. Tech. Report 99-R-034, LORIA (1999)
Kusano, K., Matsubara, W., Ishino, A., Bannai, H., Shinohara, A.: New lower bounds for the maximum number of runs in a string. CoRR, abs/0804.1214 (2008)
Lothaire, M.: Combinatorics on Words. Addison-Wesley, Reading (1983)
Puglisi, S.J., Simpson, J., Smyth, W.F.: How many runs can a string contain? Theor. Comput. Sci. 401(1-3), 165–171 (2008)
Rytter, W.: The number of runs in a string: Improved analysis of the linear upper bound. In: Durand, B., Thomas, W. (eds.) STACS 2006. LNCS, vol. 3884, pp. 184–195. Springer, Heidelberg (2006)
Rytter, W.: The number of runs in a string. Inf. Comput. 205(9), 1459–1469 (2007)
Simpson, J.: Modified Padovan words and the maximum number of runs in a word. Australasian J. of Comb. 46, 129–145 (2010)
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Crochemore, M., Kubica, M., Radoszewski, J., Rytter, W., Waleń, T. (2011). On the Maximal Sum of Exponents of Runsin a String. In: Iliopoulos, C.S., Smyth, W.F. (eds) Combinatorial Algorithms. IWOCA 2010. Lecture Notes in Computer Science, vol 6460. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-19222-7_2
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DOI: https://doi.org/10.1007/978-3-642-19222-7_2
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