Proceedings of the London Mathematical Society Advance Access originally published online on August 21, 2007
Proceedings of the London Mathematical Society 2007 95(3):778-812; doi:10.1112/plms/pdm027
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© 2007 London Mathematical Society
Measures of pseudorandomness for finite sequences: typical values
Raymond and Beverly Sackler Faculty of Exact Sciences
Tel Aviv University
Tel Aviv 69978
Israel
noga{at}math.tau.ac.il
Instituto de Matemática e Estatística
Universidade de São Paulo
Rua do Matão 1010
05508–090 São Paulo, SP
Brazil
Institut de Mathématiques de Luminy
CNRS-UPR901
163 av. de Luminy, case 907
13288 Marseille cedex 9
France
mauduit{at}iml.univ-mrs.fr
IMPA
Estrada Dona Castorina 110
22460–320 Rio de Janeiro, RJ
Brazil
gugu{at}impa.br
Department of Mathematics and Computer Science
Emory University
Atlanta, GA 30322
USA
rodl{at}mathcs.emory.edu
Received 12 April 2006.
Mauduit and Sárközy introduced and studied certain numerical parameters associated to finite binary sequences EN
{–1, 1}N in order to measure their level of randomness. Those parameters, the normality measure
(EN), the well-distribution measure W(EN), and the correlation measure Ck(EN) of order k, focus on different combinatorial aspects of EN. In their work, amongst others, Mauduit and Sárközy (i) investigated the relationship among those parameters and their minimal possible value, (ii) estimated
(EN), W(EN) and Ck(EN) for certain explicitly constructed sequences EN suggested to have a pseudorandom nature, and (iii) investigated the value of those parameters for genuinely random sequences EN.
In this paper, we continue the work in the direction of (iii) above and determine the order of magnitude of
(EN), W(EN) and Ck(EN) for typical EN. We prove that, for most EN
{–1, 1}N, both W(EN) and
(EN) are of order
N, while Ck(EN) is of order
for any given 2
k
N/4.
2000 Mathematics Subject Classification 68R15.
Part of this work was done at IMPA, whose hospitality the authors gratefully acknowledge. This research was partially supported by IM-AGIMB/IMPA. The first author was partially supported by the Israel Science Foundation, by a USA-Israeli BSF grant, by NSF grant CCR-0324906, by the James Wolfensohn fund and by the State of New Jersey. The second author was partially supported by FAPESP and CNPq through a Temático-ProNEx project (Proc. FAPESP 2003/09925-5) and by CNPq (Proc. 306334/2004-6 and 479882/2004-5). The third author was partially supported by the Brazil/France Agreement in Mathematics (Proc. CNPq 60-0014/01-5 and 69-0140/03-7). The fourth author was partially supported by MCT/CNPq through a ProNEx project (Proc. CNPq 662416/1996-1) and by CNPq (Proc. 300647/95-6). The fifth author was partially supported by NSF Grant DMS 0300529. The authors gratefully acknowledge the support of a CNPq/NSF cooperative grant (910064/99-7, 0072064).