for A being preIfWhileAlgebra
for B being Subset of A
for n being Nat holds
( EmptyIns A in B |^ (n + 1) & ( for C, I1, I2 being Element of A st C in B |^ n & I1 in B |^ n & I2 in B |^ n holds
( I1 \; I2 in B |^ (n + 1) & if-then-else (C,I1,I2) in B |^ (n + 1) & while (C,I1) in B |^ (n + 1) ) ) )