for A being preIfWhileAlgebra st A is free holds
for C, I1, I2, D, J1, J2 being Element of A holds
( if-then-else (C,I1,I2) <> C & if-then-else (C,I1,I2) <> I1 & if-then-else (C,I1,I2) <> I2 & if-then-else (C,I1,I2) <> while (D,J1) & ( if-then-else (C,I1,I2) = if-then-else (D,J1,J2) implies ( C = D & I1 = J1 & I2 = J2 ) ) )