-- Mathlib/Algebra/Ring/Subsemiring/Basic.lean
theorem closure_induction₂ {s : Set R} {p : (x y : R) → x ∈ closure s → y ∈ closure s → Prop}
    (mem_mem : ∀ (x) (y) (hx : x ∈ s) (hy : y ∈ s), p x y (subset_closure hx) (subset_closure hy))
    (zero_left : ∀ x hx, p 0 x (zero_mem _) hx) (zero_right : ∀ x hx, p x 0 hx (zero_mem _))
    (one_left : ∀ x hx, p 1 x (one_mem _) hx) (one_right : ∀ x hx, p x 1 hx (one_mem _))
    (add_left : ∀ x y z hx hy hz, p x z hx hz → p y z hy hz → p (x + y) z (add_mem hx hy) hz)
    (add_right : ∀ x y z hx hy hz, p x y hx hy → p x z hx hz → p x (y + z) hx (add_mem hy hz))
    (mul_left : ∀ x y z hx hy hz, p x z hx hz → p y z hy hz → p (x * y) z (mul_mem hx hy) hz)
    (mul_right : ∀ x y z hx hy hz, p x y hx hy → p x z hx hz → p x (y * z) hx (mul_mem hy hz))
    {x y : R} (hx : x ∈ closure s) (hy : y ∈ closure s) :
    p x y hx hy

Proof state:
R : Type u
inst✝ : NonAssocSemiring R
s : Set R
p : (x y : R) → x ∈ closure s → y ∈ closure s → Prop
mem_mem : ∀ (x y : R) (hx : x ∈ s) (hy : y ∈ s), p x y ⋯ ⋯
zero_left : ∀ (x : R) (hx : x ∈ closure s), p 0 x ⋯ hx
zero_right : ∀ (x : R) (hx : x ∈ closure s), p x 0 hx ⋯
one_left : ∀ (x : R) (hx : x ∈ closure s), p 1 x ⋯ hx
one_right : ∀ (x : R) (hx : x ∈ closure s), p x 1 hx ⋯
add_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x + y) z ⋯ hz
add_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y + z) hx ⋯
mul_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x * y) z ⋯ hz
mul_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y * z) hx ⋯
x y : R
hx : x ∈ closure s
hy : y ∈ closure s
⊢ p x y hx hy

Tactic:
induction hy using closure_induction with
| mem z hz => induction hx using closure_induction with
  | mem _ h => exact mem_mem _ _ h hz
  | zero => exact zero_left _ _
  | one => exact one_left _ _
  | mul _ _ _ _ h₁ h₂ => exact mul_left _ _ _ _ _ _ h₁ h₂
  | add _ _ _ _ h₁ h₂ => exact add_left _ _ _ _ _ _ h₁ h₂
| zero => exact zero_right x hx
| one => exact one_right x hx
| mul _ _ _ _ h₁ h₂ => exact mul_right _ _ _ _ _ _ h₁ h₂
| add _ _ _ _ h₁ h₂ => exact add_right _ _ _ _ _ _ h₁ h₂

Result:
no goals

Proof state:
case mem.zero
R : Type u
inst✝ : NonAssocSemiring R
s : Set R
p : (x y : R) → x ∈ closure s → y ∈ closure s → Prop
mem_mem : ∀ (x y : R) (hx : x ∈ s) (hy : y ∈ s), p x y ⋯ ⋯
zero_left : ∀ (x : R) (hx : x ∈ closure s), p 0 x ⋯ hx
zero_right : ∀ (x : R) (hx : x ∈ closure s), p x 0 hx ⋯
one_left : ∀ (x : R) (hx : x ∈ closure s), p 1 x ⋯ hx
one_right : ∀ (x : R) (hx : x ∈ closure s), p x 1 hx ⋯
add_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x + y) z ⋯ hz
add_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y + z) hx ⋯
mul_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x * y) z ⋯ hz
mul_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y * z) hx ⋯
x y z : R
hz : z ∈ s
⊢ p 0 z ⋯ ⋯

Tactic:
exact zero_left _ _

Result:
no goals

Proof state:
case mem.add
R : Type u
inst✝ : NonAssocSemiring R
s : Set R
p : (x y : R) → x ∈ closure s → y ∈ closure s → Prop
mem_mem : ∀ (x y : R) (hx : x ∈ s) (hy : y ∈ s), p x y ⋯ ⋯
zero_left : ∀ (x : R) (hx : x ∈ closure s), p 0 x ⋯ hx
zero_right : ∀ (x : R) (hx : x ∈ closure s), p x 0 hx ⋯
one_left : ∀ (x : R) (hx : x ∈ closure s), p 1 x ⋯ hx
one_right : ∀ (x : R) (hx : x ∈ closure s), p x 1 hx ⋯
add_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x + y) z ⋯ hz
add_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y + z) hx ⋯
mul_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x * y) z ⋯ hz
mul_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y * z) hx ⋯
x y z : R
hz : z ∈ s
x✝ y✝ : R
hx✝ : x✝ ∈ closure s
hy✝ : y✝ ∈ closure s
h₁ : p x✝ z hx✝ ⋯
h₂ : p y✝ z hy✝ ⋯
⊢ p (x✝ + y✝) z ⋯ ⋯

Tactic:
exact add_left _ _ _ _ _ _ h₁ h₂

Result:
no goals

Proof state:
case mem.mul
R : Type u
inst✝ : NonAssocSemiring R
s : Set R
p : (x y : R) → x ∈ closure s → y ∈ closure s → Prop
mem_mem : ∀ (x y : R) (hx : x ∈ s) (hy : y ∈ s), p x y ⋯ ⋯
zero_left : ∀ (x : R) (hx : x ∈ closure s), p 0 x ⋯ hx
zero_right : ∀ (x : R) (hx : x ∈ closure s), p x 0 hx ⋯
one_left : ∀ (x : R) (hx : x ∈ closure s), p 1 x ⋯ hx
one_right : ∀ (x : R) (hx : x ∈ closure s), p x 1 hx ⋯
add_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x + y) z ⋯ hz
add_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y + z) hx ⋯
mul_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x * y) z ⋯ hz
mul_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y * z) hx ⋯
x y z : R
hz : z ∈ s
x✝ y✝ : R
hx✝ : x✝ ∈ closure s
hy✝ : y✝ ∈ closure s
h₁ : p x✝ z hx✝ ⋯
h₂ : p y✝ z hy✝ ⋯
⊢ p (x✝ * y✝) z ⋯ ⋯

Tactic:
exact mul_left _ _ _ _ _ _ h₁ h₂

Result:
no goals

Proof state:
case add
R : Type u
inst✝ : NonAssocSemiring R
s : Set R
p : (x y : R) → x ∈ closure s → y ∈ closure s → Prop
mem_mem : ∀ (x y : R) (hx : x ∈ s) (hy : y ∈ s), p x y ⋯ ⋯
zero_left : ∀ (x : R) (hx : x ∈ closure s), p 0 x ⋯ hx
zero_right : ∀ (x : R) (hx : x ∈ closure s), p x 0 hx ⋯
one_left : ∀ (x : R) (hx : x ∈ closure s), p 1 x ⋯ hx
one_right : ∀ (x : R) (hx : x ∈ closure s), p x 1 hx ⋯
add_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x + y) z ⋯ hz
add_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y + z) hx ⋯
mul_left :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x z hx hz → p y z hy hz → p (x * y) z ⋯ hz
mul_right :
  ∀ (x y z : R) (hx : x ∈ closure s) (hy : y ∈ closure s) (hz : z ∈ closure s),
    p x y hx hy → p x z hx hz → p x (y * z) hx ⋯
x y : R
hx : x ∈ closure s
x✝ y✝ : R
hx✝ : x✝ ∈ closure s
hy✝ : y✝ ∈ closure s
h₁ : p x x✝ hx hx✝
h₂ : p x y✝ hx hy✝
⊢ p x (x✝ + y✝) hx ⋯

Tactic:
exact add_right _ _ _ _ _ _ h₁ h₂

Result:
no goals