lean4-htt/tests/lean/974.lean
2022-01-25 18:47:03 -08:00

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inductive Formula : Nat → Type u
| bot : Formula n
| imp (f₁ f₂ : Formula n ) : Formula n
| all (f : Formula (n+1)) : Formula n
def Formula.count_quantifiers : {n:Nat} → Formula n → Nat
| _, imp f₁ f₂ => f₁.count_quantifiers + f₂.count_quantifiers
| _, all f => f.count_quantifiers + 1
| _, _ => 0
attribute [simp] Formula.count_quantifiers
#check @Formula.count_quantifiers._eq_1
#check @Formula.count_quantifiers._eq_2
#check @Formula.count_quantifiers._eq_3
@[simp] def Formula.count_quantifiers2 : Formula n → Nat
| imp f₁ f₂ => f₁.count_quantifiers2 + f₂.count_quantifiers2
| all f => f.count_quantifiers2 + 1
| _ => 0