10 lines
225 B
Text
10 lines
225 B
Text
example (f : nat → nat) (p : nat → Prop)
|
|
(h₁ : ∀ x, f (nat.succ x) = 1)
|
|
(h₂ : ¬ p 0)
|
|
(a : nat)
|
|
(h₃ : p (f a)) : f (f a) = 1 :=
|
|
begin
|
|
cases f a,
|
|
contradiction,
|
|
apply h₁
|
|
end
|