Get all the vertices.
Get all the relations.
closure min max pred creates the clansitive closure of max
using the precedence relation pred. The closure will not
contain any keys before the the one specified in min.
closure min max pred
output ppf vertex edges name create aand dumps the graph
contents on ppf. The graph is defined by its vertex and
edges. name is the name of the output graph.
output ppf vertex edges name
Compute the minimum vertex.
Compute the maximun vertex.
Expose the graph internals.
Expose the graph as a pair of vertices and edges.
Import a graph.
The base functions over graph internals.
Build a graph.