tree

mathematics, data A directed acyclic graph; i.e. a graph

wherein there is only one route between any pair of nodes,

and there is a notion of "toward top of the tree" (i.e. the

root node), and its opposite direction, toward the leaves.

A tree with n nodes has n-1 edges.

Although maybe not part of the widest definition of a tree, a

common constraint is that no node can have more than one

parent. Moreover, for some applications, it is necessary to

consider a node's daughter nodes to be an ordered list,

instead of merely a set.

As a data structure in computer programs, trees are used in

everything from B-trees in databases and file systems, to

game trees in game theory, to syntax trees in a human or

computer languages.

(1998-11-12)