Unary vertex

Unary vertex --- унарная вершина.

For a given [math]\displaystyle{ m }[/math]-ary tree, a node with only one son is called an unary node. A node with two sons is called binary; a node which has the maximal allowable number [math]\displaystyle{ m }[/math] sons or which is a leaf is said to be saturated, otherwise it is said to be unsaturated.