Proof: Do Stack At Unchanged 17
Let's prove the following theorem:
if the following are true:
- expression state at time 17 = "begin_expr"
- stack at time 17 = [ ]
then stack at time 18 = [ ]
Proof:
Given
1 | expression state at time 17 = "begin_expr" |
---|---|
2 | stack at time 17 = [ ] |
# | Claim | Reason |
---|---|---|
1 | stack at time (17 + 1) = stack at time 17 | if expression state at time 17 = "begin_expr", then stack at time (17 + 1) = stack at time 17 |
2 | stack at time (17 + 1) = [ ] | if stack at time (17 + 1) = stack at time 17 and stack at time 17 = [ ], then stack at time (17 + 1) = [ ] |
3 | 17 + 1 = 18 | 17 + 1 = 18 |
4 | stack at time (17 + 1) = stack at time 18 | if 17 + 1 = 18, then stack at time (17 + 1) = stack at time 18 |
5 | stack at time 18 = [ ] | if stack at time (17 + 1) = stack at time 18 and stack at time (17 + 1) = [ ], then stack at time 18 = [ ] |
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