reserve G for _Graph;

theorem Th36:
  G is loopless iff VertexAdjSymRel(G) is irreflexive
proof
  thus G is loopless implies VertexAdjSymRel(G) is irreflexive;
  assume VertexAdjSymRel(G) is irreflexive;
  then VertexAdjSymRel(G) misses id the_Vertices_of G by GLIBPRE0:11;
  hence G is loopless by Lm3;
end;
