-- Mathlib/LinearAlgebra/CliffordAlgebra/Fold.lean
theorem left_induction {P : CliffordAlgebra Q → Prop} (algebraMap : ∀ r : R, P (algebraMap _ _ r))
    (add : ∀ x y, P x → P y → P (x + y)) (ι_mul : ∀ x m, P x → P (ι Q m * x)) : ∀ x, P x

Proof state:
R : Type u_1
M : Type u_2
inst✝² : CommRing R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
Q : QuadraticForm R M
P : CliffordAlgebra Q → Prop
algebraMap : ∀ (r : R), P ((_root_.algebraMap R (CliffordAlgebra Q)) r)
add : ∀ (x y : CliffordAlgebra Q), P x → P y → P (x + y)
ι_mul : ∀ (x : CliffordAlgebra Q) (m : M), P x → P ((ι Q) m * x)
⊢ ∀ (x : CliffordAlgebra Q), P x

Tactic:
refine reverse_involutive.surjective.forall.2 ?_

Result:
R : Type u_1
M : Type u_2
inst✝² : CommRing R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
Q : QuadraticForm R M
P : CliffordAlgebra Q → Prop
algebraMap : ∀ (r : R), P ((_root_.algebraMap R (CliffordAlgebra Q)) r)
add : ∀ (x y : CliffordAlgebra Q), P x → P y → P (x + y)
ι_mul : ∀ (x : CliffordAlgebra Q) (m : M), P x → P ((ι Q) m * x)
⊢ ∀ (x : CliffordAlgebra Q), P (reverse x)

Proof state:
case add
R : Type u_1
M : Type u_2
inst✝² : CommRing R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
Q : QuadraticForm R M
P : CliffordAlgebra Q → Prop
algebraMap : ∀ (r : R), P ((_root_.algebraMap R (CliffordAlgebra Q)) r)
add : ∀ (x y : CliffordAlgebra Q), P x → P y → P (x + y)
ι_mul : ∀ (x : CliffordAlgebra Q) (m : M), P x → P ((ι Q) m * x)
x✝ y✝ : CliffordAlgebra Q
hx : P (reverse x✝)
hy : P (reverse y✝)
⊢ P (reverse (x✝ + y✝))

Tactic:
simpa only [map_add] using add _ _ hx hy

Result:
no goals

Proof state:
R : Type u_1
M : Type u_2
inst✝² : CommRing R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
Q : QuadraticForm R M
P : CliffordAlgebra Q → Prop
algebraMap : ∀ (r : R), P ((_root_.algebraMap R (CliffordAlgebra Q)) r)
add : ∀ (x y : CliffordAlgebra Q), P x → P y → P (x + y)
ι_mul : ∀ (x : CliffordAlgebra Q) (m : M), P x → P ((ι Q) m * x)
x : CliffordAlgebra Q
⊢ P (reverse x)

Tactic:
induction x using CliffordAlgebra.right_induction with
| algebraMap r => simpa only [reverse.commutes] using algebraMap r
| add _ _ hx hy => simpa only [map_add] using add _ _ hx hy
| mul_ι _ _ hx => simpa only [reverse.map_mul, reverse_ι] using ι_mul _ _ hx

Result:
no goals

Proof state:
R : Type u_1
M : Type u_2
inst✝² : CommRing R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
Q : QuadraticForm R M
P : CliffordAlgebra Q → Prop
algebraMap : ∀ (r : R), P ((_root_.algebraMap R (CliffordAlgebra Q)) r)
add : ∀ (x y : CliffordAlgebra Q), P x → P y → P (x + y)
ι_mul : ∀ (x : CliffordAlgebra Q) (m : M), P x → P ((ι Q) m * x)
⊢ ∀ (x : CliffordAlgebra Q), P (reverse x)

Tactic:
intro x

Result:
R : Type u_1
M : Type u_2
inst✝² : CommRing R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
Q : QuadraticForm R M
P : CliffordAlgebra Q → Prop
algebraMap : ∀ (r : R), P ((_root_.algebraMap R (CliffordAlgebra Q)) r)
add : ∀ (x y : CliffordAlgebra Q), P x → P y → P (x + y)
ι_mul : ∀ (x : CliffordAlgebra Q) (m : M), P x → P ((ι Q) m * x)
x : CliffordAlgebra Q
⊢ P (reverse x)

Proof state:
case algebraMap
R : Type u_1
M : Type u_2
inst✝² : CommRing R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
Q : QuadraticForm R M
P : CliffordAlgebra Q → Prop
algebraMap : ∀ (r : R), P ((_root_.algebraMap R (CliffordAlgebra Q)) r)
add : ∀ (x y : CliffordAlgebra Q), P x → P y → P (x + y)
ι_mul : ∀ (x : CliffordAlgebra Q) (m : M), P x → P ((ι Q) m * x)
r : R
⊢ P (reverse ((_root_.algebraMap R (CliffordAlgebra Q)) r))

Tactic:
simpa only [reverse.commutes] using algebraMap r

Result:
no goals

Proof state:
case mul_ι
R : Type u_1
M : Type u_2
inst✝² : CommRing R
inst✝¹ : AddCommGroup M
inst✝ : Module R M
Q : QuadraticForm R M
P : CliffordAlgebra Q → Prop
algebraMap : ∀ (r : R), P ((_root_.algebraMap R (CliffordAlgebra Q)) r)
add : ∀ (x y : CliffordAlgebra Q), P x → P y → P (x + y)
ι_mul : ∀ (x : CliffordAlgebra Q) (m : M), P x → P ((ι Q) m * x)
m✝ : M
x✝ : CliffordAlgebra Q
hx : P (reverse x✝)
⊢ P (reverse (x✝ * (ι Q) m✝))

Tactic:
simpa only [reverse.map_mul, reverse_ι] using ι_mul _ _ hx

Result:
no goals