 reserve n for Nat;
 reserve s1 for sequence of Euclid n,
         s2 for sequence of REAL-NS n;

theorem
  for I1,I2 being non empty closed_interval Subset of REAL,
      jauge being positive-yielding Function of I1,REAL st I2 c= I1 holds
  jauge|I2 is positive-yielding Function of I2,REAL by FUNCT_2:32;
