theorem Lm6:
  (Partial_Union Equal_Div_interval(t)).(t-1) = [.0,1.[
  proof
A0: 0 <= t-1 by Lm1,XREAL_1:50;
    (Partial_Union Equal_Div_interval(t)).(t-1)
      = [. 0, (t-1 + 1)/t.[ by A0,Lm3
     .= [. 0, 1 .[ by Lm1;
    hence thesis;
  end;
