Binary Trees

A binary tree T is defined as a finite set of elements, called nodes, such that :
(a) T is empty (called the NULL tree or empty tree) or
(b) T contains a distinguished node R, called the root of T, and the remaining nodes of T form an ordered pair of disjoint binary trees T1 and T2 .

A binary tree is a tree in which no node can have more than two subtrees. In other words, a node can have zero, one, or two subtrees. These subtrees are designated as the left subtree and right subtree.