| ⊢ | f ∧fin w ≡ f ; (w ∧empty) | AndFinEqvChopStateAndEmpty | 
Proof for  ⊃ :
| 1 | ⊢ f ; empty ≡ f                                    | |
| 2  | ⊢ empty ⊃ (w ∧empty) ∨ (¬w ∧empty)             | |
| 3  | ⊢ f ; empty ⊃ f ; (w ∧empty) ∨ f ; (¬w ∧empty) | |
| 4  | ⊢ f ; (¬w ∧empty) ⊃ (¬w ∧empty)                 | |
| 5  | ⊢  (¬w ∧empty) ⊃¬fin w                         | |
| 6  | ⊢ f ⊃ f ; (w ∧empty) ∨¬fin w                   | |
| 7  | ⊢ f ∧fin w ⊃ f ; (w ∧empty)                        | 
qed
Proof for ⊂:
| 1 | ⊢ f ; (w ∧empty) ⊃ f ; empty       | |
| 2  | ⊢ f ; empty ≡ f                    | |
| 3  | ⊢ f ; (w ∧empty) ⊃ (w ∧empty) | |
| 4  | ⊢  (w ∧empty) ⊃fin w            | |
| 5  | ⊢ f ; (w ∧empty) ⊃ f ∧fin w    | 
qed
The following is a lemma used in the proof of theorem FinChopEqvDiamond.