Availability::- use_module(library(ugraphs)).(can be autoloaded)
 vertices(+S_Graph, -Vertices) is det
Strips off the neighbours lists of an S-representation to produce a list of the vertices of the graph. (It is a characteristic of S-representations that every vertex appears, even if it has no neighbours.). Vertices is in the standard order of terms.
 vertices(+S_Graph, -Vertices) is det
Strips off the neighbours lists of an S-representation to produce a list of the vertices of the graph. (It is a characteristic of S-representations that every vertex appears, even if it has no neighbours.). Vertices is in the standard order of terms.