Combinatorial results for order-preserving and order-decreasing transformations

被引:13
作者
Ayik, Gonca [1 ]
Ayik, Hayrullah [2 ]
Koc, Metin [1 ]
机构
[1] Cukurova Univ, Dept Math, TR-01330 Adana, Turkey
[2] Adiyaman Univ, Dept Math, Adiyaman, Turkey
关键词
Order-preserving transformations; order-decreasing transformations; nilpotent; Catalan number; SEMIGROUPS; IDEMPOTENTS;
D O I
10.3906/mat-1010-432
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
Let O-n and C-n be the semigroup of all order-preserving transformations and of all order-preserving and order-decreasing transformations on the finite set X-n = {1,2, ..., n}, respectively. Let Fix(alpha) = {x is an element of X-n : x alpha = x} for any transformation alpha. In this paper; for any Y subset of X-n, we find the cardinalities of the sets O-n,O-Y = {alpha is an element of O-n : Fix(alpha) = Y} and C-n,C-Y = {alpha is an element of C-n : Fix(alpha) = Y}. Moreover; we find the numbers of transformations of O-n and C-n with r fixed points.
引用
收藏
页码:617 / 625
页数:9
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