
theorem Th16:
  for L1, L2 being up-complete non empty Poset st the RelStr of
  L1 = the RelStr of L2 holds Sigma L1 = Sigma L2
proof
  let L1, L2 be up-complete non empty Poset;
  assume the RelStr of L1 = the RelStr of L2;
  then
A1: the RelStr of Sigma L2 = the RelStr of L1 by YELLOW_9:def 4;
  then
  the RelStr of Sigma L1 = the RelStr of L1 & Sigma L2 is TopAugmentation
  of L1 by YELLOW_9:def 4;
  hence thesis by A1,Th13;
end;
