2.1 Introduction

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Trees are a special case of a graph data structure. The connections radiate out from a single root without cross connections.

The tree has nodes (shown with circles) that are connected with branches. Each node will have a parent node (except for the root) and may have multiple child nodes.

In an unordered tree the children of a node can be unordered, however in an ordered tree the children take priority, often by listing them in order.

A Boolean tree applies operators for each of the nodes