reserve G for _Graph;
reserve V for non empty set, E for Relation of V;
reserve E for symmetric Relation of V;
reserve G for GraphFromSymRel of V, E;

theorem
  for X being set holds G.edgesInOut(X) c= (E|X) \/ (X|`E)
proof
  let X be set;
  (E|X) \/ (X|`E) = createGraph(V,E).edgesInOut(X) by Th80;
  hence thesis by GLIB_000:76;
end;
