DMTCS Proceedings, 21st International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2009)

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Record statistics in integer compositions

Arnold Knopfmacher, Toufik Mansour

Abstract


A composition σ=a1 a2…am of n is an ordered collection of positive integers whose sum is n. An element ai in σ is a strong (weak) record if ai> aj (ai≥aj) for all j=1,2,…,i-1. Furthermore, the position of this record is i. We derive generating functions for the total number of strong (weak) records in all compositions of n, as well as for the sum of the positions of the records in all compositions of n, where the parts ai belong to a fixed subset A of the natural numbers. In particular when A=, we find the asymptotic mean values for the number, and for the sum of positions, of records in compositions of n.

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