G = underlyingGraph D
The underlying graph of a digraph is the simple graph constructed by all edges {u,v} such that (u,v) or (v,u) is a directed edge in the digraph.
i1 : D = digraph hashTable{1 => {2,3}, 2 => {1,3}, 3 => {}};
i2 : underlyingGraph D o2 = Graph{1 => {2, 3}} 2 => {1, 3} 3 => {1, 2} o2 : Graph
The object underlyingGraph is a method function.