lean4-htt/doc/examples/Certora2022/ex17.lean
2022-11-21 17:02:28 -08:00

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/- More tactics -/
example (p q : Nat → Prop) : (∃ x, p x ∧ q x) → ∃ x, q x ∧ p x := by
intro h
cases h with
| intro x hpq =>
cases hpq with
| intro hp hq =>
exists x
example : p ∧ q → q ∧ p := by
intro p
cases p
constructor <;> assumption
example : p ∧ ¬ p → q := by
intro h
cases h
contradiction