Programming languages

hey

I have question on my assignment I couldn't solve and I have to submit it after two hours

It's hard tho

here :

1. Explain the four criteria for proving the correctness of a logical pretest loop construct of each of the following forms:

a. while  m <> n  do  m = m + 2  end   { m = n } 

b. while  k > 2  do  k = k / 2  end  { k = 2 }