A.37 library(ugraphs): Unweighted Graphs
AllApplicationManualNameSummaryHelp

Availability::- use_module(library(ugraphs)).(can be autoloaded)
Sourcereachable(+Vertex, +Graph, -Vertices)
Unify Vertices with the set of all vertices in Graph that are reachable from Vertex. Example: 
?- reachable(1,[1-[3,5],2-[4],3-[],4-[5],5-[]],V).
V = [1, 3, 5]

ClioPatria (version V3.1.1-21-gb8003bb)