reserve GS for GraphStruct;
reserve G,G1,G2,G3 for _Graph;
reserve e,x,x1,x2,y,y1,y2,E,V,X,Y for set;
reserve n,n1,n2 for Nat;
reserve v,v1,v2 for Vertex of G;

theorem ::: obsolete as reductions are added
  for V being non empty set, E being set, S,T being Function of E,V holds
    the_Vertices_of createGraph(V,E,S,T) = V &
    the_Edges_of createGraph(V,E,S,T) = E &
    the_Source_of createGraph(V,E,S,T) = S &
    the_Target_of createGraph(V,E,S,T) = T;
