set G = createGraph (V,E,S,T);
for e1, e2, v1, v2 being object st e1 Joins v1,v2, createGraph (V,E,S,T) & e2 Joins v1,v2, createGraph (V,E,S,T) holds
e1 = e2 ;
then A1: createGraph (V,E,S,T) is non-multi ;
createGraph (V,E,S,T) is loopless ;
hence createGraph (V,E,S,T) is simple by A1; :: thesis: verum