fixed link

A link which remains in the same position during graph layout or link layout. If the user specifies a link as fixed, layout algorithms are not allowed to reshape this link.

fixed node

A node which remains in the same position during graph layout or link layout. If the user specifies a node as fixed, layout algorithms are not allowed to move this node.

flat graph

The converse of a nested graph: a graph of which no node is itself a graph. See nested graph.

Force-directed layout

A class of layout algorithms for creating straight-line drawings of undirected graphs based on an iterative computation of the position of the nodes according to a set of attractive and repulsive forces. These forces are computed in such a way that they tend to produce a layout with only a few link crossings or no link crossings.