Record statistics in a random composition

  • Authors:
  • Arnold Knopfmacher;Toufik Mansour

  • Affiliations:
  • The John Knopfmacher Centre for Applicable Analysis and Number Theory, Department of Mathematics, University of the Witwatersrand, P.O. Wits, 2050, Johannesburg, South Africa;Department of Mathematics, University of Haifa, 31905 Haifa, Israel

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2012

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Abstract

A composition@s=a"1a"2...a"m of n is an ordered collection of positive integers whose sum is n. An element a"i in @s is a strong (weak) record if a"ia"j (a"i=a"j) 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 a"i belong to A=[d]:={1,2,...,d} or A=N. In particular when A=N, we find the asymptotic mean values for the number, and for the sum of positions of records in compositions of n.