Question

The Heaviside step function is a mathematical function defined by h(x) := ( 1 : x ≥ 0 0 : x < 0 that is to say, h(x) is 1 for non-negative x and 0 for negative x. In this question we will prove that the following code computes h(x) if (x >= 0): y = 1 else: y = 0

a) Define a predicate p(x, y), written solely in terms of logical ANDs and ORs, inequalities and equalities, which says that y = h(x). Hint: Create a predicate for each of the two cases in the definition of h(x) and combine them with a logical OR. (1 mark)

b) Write a proof of correctness to show that the code fragment above correctly computes y = h(x). Do this by showing that p(x, y) you defined in the previous part is a post-condition. Hints: As a special case of the assignment rule, if you have an assignment x = E you can take {x = E} as an assertion. Also, you may want to look for inspiration at the proof of correctness for computing max in tutorial 5.

I need answer for part B as i have already done part a thanks

Answer 1

-hCt) You have an ascyomed χ°C taka son asertion