Heap ordered trees are planted plane trees, labelled in such a way that the labels always increase from the root to a leaf. We study two parameters, assuming that p of the n nodes ...
The problem of counting plane trees with n edges and an even or an odd number of leaves has been recently studied by Eu, Liu and Yeh, in connection with an identity on coloring ne...
William Y. C. Chen, Louis W. Shapiro, Laura L. M. ...
Abstract. A leaf of a plane tree is called an old leaf if it is the leftmost child of its parent, and it is called a young leaf otherwise. In this paper we enumerate plane trees wi...
William Y. C. Chen, Emeric Deutsch, Sergi Elizalde
We consider plane trees whose vertices are given labels from the set {1, 2, . . . , k} in such a way that the sum of the labels along any edge is at most k + 1; it turns out that ...