for G1 being _Graph
for G2 being DLGraphComplement of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inNeighbors() = (the_Vertices_of G2) \ (v1 .inNeighbors()) & v2 .outNeighbors() = (the_Vertices_of G2) \ (v1 .outNeighbors()) )