theorem
 for e,x being object holds
  e Joins x,x,G implies G.walkOf(x,e,x) is Cycle-like
proof let e,x be object;
  set W = G.walkOf(x,e,x);
  assume e Joins x,x,G;
  then len W = 3 by Th13;
  then W is non trivial by Lm54;
  hence thesis;
end;
