Proof: Do Stack At Unchanged 71

Let's prove the following theorem:

if the following are true:
  • expression state at time 71 = "return"
  • stack at time 71 = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ]

then stack at time 72 = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ]

Proof:

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Given
1 expression state at time 71 = "return"
2 stack at time 71 = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ]
Proof Table
# Claim Reason
1 stack at time (71 + 1) = stack at time 71 if expression state at time 71 = "return", then stack at time (71 + 1) = stack at time 71
2 stack at time (71 + 1) = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ] if stack at time (71 + 1) = stack at time 71 and stack at time 71 = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ], then stack at time (71 + 1) = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ]
3 71 + 1 = 72 71 + 1 = 72
4 stack at time (71 + 1) = stack at time 72 if 71 + 1 = 72, then stack at time (71 + 1) = stack at time 72
5 stack at time 72 = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ] if stack at time (71 + 1) = stack at time 72 and stack at time (71 + 1) = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ], then stack at time 72 = [ program context with variables: [ entry p: (Python reference 0), [ ] ] and expression state: (expression state with parent stack: [ ] arguments: [ ] values: [ ] line: 9 tab: 0) and control map: [ entry 0: (pair ("class", "Person")), [ ] ], [ ] ]

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