exact f_stable
case false
f : Bool → Bool → Bool
f_stable : f false false = false
n : Nat
hfft : f false true = false
⊢ f false false = false

case true
f : Bool → Bool → Bool
f_stable : f false false = false
n : Nat
hfft : f false true = false
⊢ f false true = false
case true
f : Bool → Bool → Bool
f_stable : f false false = false
n : Nat
hfft : f false true = false
⊢ f false true = false