reserve G for _Graph;

theorem
  for G being non _trivial _Graph, v being Vertex of G
  for H being removeVertex of G, v st v is isolated
  holds VertexAdjSymRel(H) = VertexAdjSymRel(G)
proof
  let G be non _trivial _Graph, v be Vertex of G;
  let H be removeVertex of G, v;
  assume v is isolated;
  then VertexDomRel(H) = VertexDomRel(G) by Th24;
  hence thesis;
end;
