underlyingGraph(MomentGraph) -- the underlying (undirected) graph of a moment graph

i1 : G = momentGraph projectiveSpace 3

o1 = a "moment graph" on 4 vertices with 6 edges 

o1 : MomentGraph

i2 : underlyingGraph G

o2 = Graph{set {0} => {set {1}, set {2}, set {3}}}
           set {1} => {set {0}, set {2}, set {3}}
           set {2} => {set {0}, set {1}, set {3}}
           set {3} => {set {0}, set {1}, set {2}}

o2 : Graph