Claesson, Anders (2005) Counting segmented permutations using bicoloured Dyck paths. The Electronic Journal of Combinatorics, 12. ISSN 1077-8926Full text not available in this repository. Request a copy from the Strathclyde author
A bicoloured Dyck path is a Dyck path in which each up-step is assigned one of two colours, say, red and green. We say that a permutation π is σ-segmented if every occurrence o of σ in π is a segment-occurrence (i.e., o is a contiguous subword in π). We show combinatorially the following two results: The 132-segmented permutations of length n with k occurrences of 132 are in one-to-one correspondence with bicoloured Dyck paths of length 2n−4k with k red up-steps. Similarly, the 123-segmented permutations of length n with k occurrences of 123 are in one-to-one correspondence with bicoloured Dyck paths of length 2n−4k with k red up-steps, each of height less than 2. We enumerate the permutations above by enumerating the corresponding bicoloured Dyck paths. More generally, we present a bivariate generating function for the number of bicoloured Dyck paths of length 2n with k red up-steps, each of height less than h. This generating function is expressed in terms of Chebyshev polynomials of the second kind.
|Keywords:||bicoloured Dyck path, Dyck path, segmented permutations, Electronic computers. Computer science, Computational Theory and Mathematics, Geometry and Topology, Theoretical Computer Science|
|Subjects:||Science > Mathematics > Electronic computers. Computer science|
|Department:||Faculty of Science > Computer and Information Sciences|
|Depositing user:||Pure Administrator|
|Date Deposited:||14 Oct 2014 13:49|
|Last modified:||07 Jan 2017 04:18|