Proof: Do Tab At Unchanged 20
Let's prove the following theorem:
if the following are true:
- expression state at time 20 = "begin_expr"
- the tab at time 20 = 2
then the tab at time 21 = 2
Proof:
Given
1 | expression state at time 20 = "begin_expr" |
---|---|
2 | the tab at time 20 = 2 |
# | Claim | Reason |
---|---|---|
1 | the tab at time (20 + 1) = the tab at time 20 | if expression state at time 20 = "begin_expr", then the tab at time (20 + 1) = the tab at time 20 |
2 | the tab at time (20 + 1) = 2 | if the tab at time (20 + 1) = the tab at time 20 and the tab at time 20 = 2, then the tab at time (20 + 1) = 2 |
3 | 20 + 1 = 21 | 20 + 1 = 21 |
4 | the tab at time (20 + 1) = the tab at time 21 | if 20 + 1 = 21, then the tab at time (20 + 1) = the tab at time 21 |
5 | the tab at time 21 = 2 | if the tab at time (20 + 1) = the tab at time 21 and the tab at time (20 + 1) = 2, then the tab at time 21 = 2 |
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