INVERSIONS IN COMPOSITIONS OF INTEGERS

被引:8
作者
Heubach, S. [1 ]
Knopfmacher, A. [2 ]
Mays, M. E. [3 ]
Munagi, A. [2 ]
机构
[1] Calif State Univ Los Angeles, Dept Math, Los Angeles, CA 90032 USA
[2] Univ Witwatersrand, John Knopfmacher Ctr Applicable Anal & Number The, Johannesburg, South Africa
[3] W Virginia Univ, Morgantown, WV 26506 USA
基金
新加坡国家研究基金会;
关键词
Composition; inversion;
D O I
10.2989/16073606.2011.594234
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
A composition of the positive integer n is a representation of n as an ordered sum of positive integers n = a(1) + a(2) + ... + am. It is well known that there are 2(n-1) compositions of n. An inversion in a composition is a pair of summands {a(i), a(j)} for which i < j and a(i) > a(j). The number of inversions of a composition is an indication of how far the composition is from a partition of n, which by convention uses a sequence of nondecreasing summands and has no inversions. We consider counting techniques for determining both the number of inversions in the set of compositions of n and the number of compositions of n with a given number of inversions. We provide explicit bijections to resolve several conjectures, and also consider asymptotic results.
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页码:187 / 202
页数:16
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