Abstract
In this paper we enumerate and give bijections for the following four sets of vertices among rooted ordered trees of a fixed size: (i) first-children of degree k at level ℓ, (ii) non-first-children of degree k at level ℓ−1, (iii) leaves having k−1 elder siblings at level ℓ, and (iv) non-leaves of outdegree k at level ℓ−1. Our results unite and generalize several previous works in the literature.
Original language | English |
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Pages (from-to) | 2123-2129 |
Number of pages | 7 |
Journal | Discrete Mathematics |
Volume | 340 |
Issue number | 9 |
DOIs | |
Publication status | Published - 2017 Sept 1 |
Keywords
- Degree
- Enumeration
- Level
- Rooted ordered tree
ASJC Scopus subject areas
- Theoretical Computer Science
- Discrete Mathematics and Combinatorics