Let X denote the set of plane trees of n+1 edges with bi-colored leaves, and 2 distinguished internal vertices. Let Y denote the set of plane trees of n edges with bi-colored leaves, and 2 distinguished vertices (not necessarily internal). Then, |X|=|Y|.
Could anyone give a bijection between X and Y?
Note: from "A Combinatorial Identity Concerning Plane Colored Trees and its Applications, Journal of Integer Sequences 20 (2017)", Theorem 6