关于逆序数相同的n级排列个数的讨论  

Discussion of the Number of Permutations with the Same Inverse Orders

作　　者：张翠[1] 张英瑞[1] 

机构地区：[1]洛阳师范学院数学科学学院,河南洛阳471022

出　　处：《洛阳师范学院学报》2010年第5期24-25,34,共3页Journal of Luoyang Normal University

摘　　要：以Wn,j表示n级排列中逆序数为j的排列的个数.本文给出了Wn,j的一个递推关系式,并证明了序列Wn,0,Wn,1,…,Wn,n(n2-1)/λ是单峰的,对数凹的.Let Wn,j be the number of n permutations which have j inverse orders. In this paper, we give a recursive formula of Wn,j, and prove that the sequence of Wn,0, Wn,1 ,..., Wn,n-1/2 is unimodal and log-concave.

关 键 词：逆序 逆序数 单峰性 对数凹性 

分 类 号：O157.1[理学—数学]