CODEWITHSUNDEEP
preconditions
Smit Shah
Smit Shah

Reputation: 111

Compute the weakest precondition

Compute the weakest precondition for each of the following assignment statements and postconditions:

a = a + 2 * b - 1 {a > 1}

attempt:

a is on both sides

0 = 2b -1

1/2 = b is the weakest precon

answer: b > 1 - a/2

how do you get this answer?

Upvotes: 1

Views: 5255

Answers (1)

Archor
Archor

Reputation: 31

Here is answer : 

a = a + 2 * b - 1 {a > 1}

We replace a in {a > 1} by a + 2 * b - 1

a + 2 * b - 1 > 1
a + 2 * b > 2
2 * b > 2 - a
b > 1 - a / 2`

I think you found the answer since but for the people who might get here looking for this answer.

Upvotes: 3

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