Other nodes represent the period of time covered by all their descendants.

Each node in the tree represents a set of matches.

The nodes at the middle level represent restrictions of the set operator.

The nodes in a value network represent people (or roles).

And these nodes, or knots, represent values that are well understood because of their position.

A node can represent a word or a word form.

Each node in this tree represents a region of the two-dimensional space.

The nodes may represent concepts, words, perceptual features, or nothing at all.

Sometimes an additional assumption is made that these internal nodes do represent ancestors.

Here each vertex (or node) represents a point of choice for a player.