Noncrossing Trees and Noncrossing Graphs
Preprint
Abstract
We give a parity reversing involution on noncrossing trees that leads to a combinatorial interpretation of a formula on noncrossing trees and symmetric ternary trees in answer to a problem proposed by Hough. We use the representation of Panholzer and Prodinger for noncrossing trees and find a correspondence between a class of noncrossing trees, called proper oncrossing trees, and the set of symmetric ternary trees. The second result of this paper is a parity reversing involution on connected noncrossing graphs which leads to a relation between the number of noncrossing trees with a given number of edges and descents and the number of connected noncrossing graphs with a given number of vertices and edges.Keywords
All Related Versions
This publication has 6 references indexed in Scilit:
- Descents in Noncrossing TreesThe Electronic Journal of Combinatorics, 2003
- Diagonally convex directed polyominoes and even trees: a bijection and related issuesDiscrete Mathematics, 2002
- Statistics on non-crossing treesDiscrete Mathematics, 2002
- Bijections for ternary trees and non-crossing treesDiscrete Mathematics, 2002
- Analytic combinatorics of non-crossing configurationsDiscrete Mathematics, 1999
- Enumeration of noncrossing trees on a circleDiscrete Mathematics, 1998