lean4-htt/tests/lean/termination_by.lean
2021-09-25 16:54:41 -07:00

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mutual
inductive Even : Nat → Prop
| base : Even 0
| step : Odd n → Even (n+1)
inductive Odd : Nat → Prop
| step : Even n → Odd (n+1)
end
termination_by measure
mutual
def f (n : Nat) :=
if n == 0 then 0 else f (n / 2) + 1
termination_by measure
end
def g' (n : Nat) :=
match n with
| 0 => 1
| n+1 => g' n * 3
termination_by
h => measure
namespace Test
mutual
def f : Nat → ααα
| 0, a, b => a
| n+1, a, b => g n a b |>.1
def g : Nat → αα → (α × α)
| 0, a, b => (a, b)
| n+1, a, b => (h n a b, a)
def h : Nat → ααα
| 0, a, b => b
| n+1, a, b => f n a b
end
termination_by
f => measure
g => measure
end Test