8. 1 Tree 1. Definition: A tree t is a finite nonempty set of elements One of these elements is called the root, and the remaining elements(if any are partitioned into trees which are called the subtrees of t8.1 Tree 1.Definition: A tree T is a finite nonempty set of elements. One of these elements is called the root, and the remaining elements(if any) are partitioned into trees which are called the subtrees of T