Restricted involutions and Motzkin paths
نویسندگان
چکیده
Given a permutation σ ∈ Sn, one can partition the set {1, 2, . . . , n} into intervals A1, . . . , At such that σ(Aj) = Aj for every j. The restrictions of σ to the intervals in the finest of these decompositions are called connected components of σ. A permutation σ with a single connected component is called connected. Given a permutation σ ∈ Sn, we define the reverse of σ to be the permutation σr = σψ, where ψ ∈ Sn is defined by ψ(i) = n + 1 − i. Similarly, the complement of σ is the permutation σc = ψσ and the reverse-complement of σ is the permutation σrc = ψσψ.
منابع مشابه
Avoiding patterns in irreducible permutations
We explore the classical pattern avoidance question in the case of irreducible permutations, i.e., those in which there is no index i such that σ(i + 1) − σ(i) = 1. The problem is addressed completely in the case of avoiding one or two patterns of length three, and several well known sequences are encountered in the process, such as Catalan, Motzkin, Fibonacci, Tribonacci, Padovan and Binary nu...
متن کاملPattern avoidance and Boolean elements in the Bruhat order on involutions
We show that the principal order ideal of an element w in the Bruhat order on involutions in a symmetric group is a Boolean lattice if and only if w avoids the patterns 4321, 45312 and 456123. Similar criteria for signed permutations are also stated. Involutions with this property are enumerated with respect to natural statistics. In this context, a bijective correspondence with certain Motzkin...
متن کاملPattern Avoidance and the Bruhat Order on Involutions
We show that the principal order ideal below an element w in the Bruhat order on involutions in a symmetric group is a Boolean lattice if and only if w avoids the patterns 4321, 45312 and 456123. Similar criteria for signed permutations are also stated. Involutions with this property are enumerated with respect to natural statistics. In this context, a bijective correspondence with certain Motz...
متن کاملParity reversing involutions on plane trees and 2-Motzkin paths
The problem of counting plane trees with n edges and an even or an odd number of leaves was studied by Eu, Liu and Yeh, in connection with an identity on coloring nets due to Stanley. This identity was also obtained by Bonin, Shapiro and Simion in their study of Schröder paths, and it was recently derived by Coker using the Lagrange inversion formula. An equivalent problem for partitions of set...
متن کاملFrom (2, 3)-Motzkin Paths to Schröder Paths
In this paper, we provide a bijection between the set of restricted (2, 3)-Motzkin paths of length n and the set of Schröder paths of semilength n. Furthermore, we give a one-to-one correspondence between the set of (2, 3)-Motzkin paths of length n and the set of little Schröder paths of semilength n + 1. By applying the bijections, we get the enumerations of Schröder paths according to the sta...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2008