layout algorithm

The process that computes new coordinates for nodes and/or new shapes for links in order to obtain a suitable representation of a graph.

layout region

In the context of graph layout, the rectangle where the graph drawing will be placed when the graph is laid out.

leaf

A node in a tree that is not the root and has at the most one incident edge; that is to say, a node that has no child nodes. The nodes of the tree are named root (one special node), leaves, and inner nodes (all nodes that are not root or leaves).

leaf recursive tree

A nested graph that is a tree and only the leaves of the tree can be subgraphs.

link

Another name for an edge in a graph. In this documentation, the term link is primarily used for edge. See also edge.

link bundle

A set of links (edges) connecting a given pair of nodes in a graph, drawn as a set of parallel lines. See multiple links.

link crossing

Link crossings occur when links intersect at places other than an incident node. Also called edge crossings. Often, layout algorithms are used to minimize the number of link crossings.