lean4-htt/tests/elab/alg.lean
Garmelon 08eb78a5b2
chore: switch to new test/bench suite (#12590)
This PR sets up the new integrated test/bench suite. It then migrates
all benchmarks and some related tests to the new suite. There's also
some documentation and some linting.

For now, a lot of the old tests are left alone so this PR doesn't become
even larger than it already is. Eventually, all tests should be migrated
to the new suite though so there isn't a confusing mix of two systems.
2026-02-25 13:51:53 +00:00

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class Semigroup (α : Type u) extends Mul α where
mul_assoc (a b c : α) : a * b * c = a * (b * c)
export Semigroup (mul_assoc)
class MulComm (α : Type u) extends Mul α where
mul_comm (a b : α) : a * b = b * a
export MulComm (mul_comm)
class CommSemigroup (α : Type u) extends Semigroup α where
mul_comm (a b : α) : a * b = b * a
instance [CommSemigroup α] : MulComm α where
mul_comm := CommSemigroup.mul_comm
class Monoid (α : Type u) extends Semigroup α, One α where
one_mul (a : α) : 1 * a = a
mul_one (a : α) : a * 1 = a
export Monoid (one_mul mul_one)
class CommMonoid (α : Type u) extends Monoid α where
mul_comm (a b : α) : a * b = b * a
instance [CommMonoid α] : CommSemigroup α where
mul_comm := CommMonoid.mul_comm
instance [CommMonoid α] : MulComm α where
mul_comm := CommSemigroup.mul_comm
class Group (α : Type u) extends Monoid α, Inv α where
mul_left_inv (a : α) : a⁻¹ * a = 1
export Group (mul_left_inv)
class CommGroup (α : Type u) extends Group α where
mul_comm (a b : α) : a * b = b * a
instance [CommGroup α] : CommMonoid α where
mul_comm := CommGroup.mul_comm
instance [CommGroup α] : MulComm α where
mul_comm := CommGroup.mul_comm
theorem inv_mul_cancel_left [Group α] (a b : α) : a⁻¹ * (a * b) = b := by
rw [← mul_assoc, mul_left_inv, one_mul]
theorem inv_eq_of_mul_eq_one [Group α] {a b : α} (h : a * b = 1) : a⁻¹ = b := by
rw [← mul_one a⁻¹, ←h, ←mul_assoc, mul_left_inv, one_mul]
theorem inv_inv [Group α] (a : α) : (a⁻¹)⁻¹ = a :=
inv_eq_of_mul_eq_one (mul_left_inv a)
theorem mul_right_inv [Group α] (a : α) : a * a⁻¹ = 1 := by
have : a⁻¹⁻¹ * a⁻¹ = 1 := by rw [mul_left_inv]
rw [inv_inv] at this
assumption
theorem mul_inv_rev [Group α] (a b : α) : (a * b)⁻¹ = b⁻¹ * a⁻¹ := by
apply inv_eq_of_mul_eq_one
rw [mul_assoc, ← mul_assoc b, mul_right_inv, one_mul, mul_right_inv]
theorem mul_inv [CommGroup α] (a b : α) : (a * b)⁻¹ = a⁻¹ * b⁻¹ := by
rw [mul_inv_rev, mul_comm]