theorem
  x = one implies x *' y = y
proof
  assume
A1: x = one;
  then ex r st x = r & DEDEKIND_CUT x = { s : s < r } by Def3;
  hence x *' y = GLUED DEDEKIND_CUT y by A1,Lm44
    .= y by Lm23;
end;
