L = nondescendants (D, v)
The nondescendants of a directed graph are all the vertexSet u of D such that u is not reachable from v.
i1 : D = digraph({a,b,c,d,e},{{a,b},{b,c},{b,d},{e,b}});
i2 : nondescendants (D, d) o2 = set {a, b, c, e} o2 : Set
The object nondescendants is a method function.