
theorem
  for G1, G2 being _Graph st G1 == G2
  holds G1 is Cycle-like implies G2 is Cycle-like
proof
  let G1, G2 be _Graph;
  assume G1 == G2;
  then consider F being PGraphMapping of G1, G2 such that
    A1: F = id G1 & F is Disomorphism by GLIBPRE0:75;
  thus thesis by A1, Th48;
end;
