Theorem: LO.FirstOrder.Arith.Model.Exponential.range_exists (Arithmetization/ISigmaZero/Exponential/Exp.lean)

State before:
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
x : M
⊢ ∃ y, Exponential x y
Tactic:
induction x using induction_iSigmaOne
State after:
case hP
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
⊢ 𝚺₁-Predicate fun x => ∃ y, Exponential x y

case zero
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
⊢ ∃ y, Exponential 0 y

case succ
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
x✝ : M
a✝ : ∃ y, Exponential x✝ y
⊢ ∃ y, Exponential (x✝ + 1) y

State before:
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
⊢ ∃ y, Exponential 0 y
Tactic:
case zero => exact ⟨1, by simp⟩
State after:
no goals

State before:
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
x : M
IH : ∃ y, Exponential x y
⊢ ∃ y, Exponential (x + 1) y
Tactic:
case succ x IH =>
  rcases IH with ⟨y, IH⟩
  exact ⟨2 * y, IH.succ⟩
State after:
no goals

State before:
case hP
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
⊢ 𝚺₁-Predicate fun x => ∃ y, Exponential x y
Tactic:
apply Definable.ex
State after:
case hP.h
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
⊢ Definable ℒₒᵣ (𝚺, 0 + 1) fun w => Exponential ((fun x => w x.succ) 0) (w 0)

State before:
case hP.h
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
⊢ Definable ℒₒᵣ (𝚺, 0 + 1) fun w => Exponential ((fun x => w x.succ) 0) (w 0)
Tactic:
definability
State after:
no goals

State before:
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
⊢ ∃ y, Exponential 0 y
Tactic:
exact ⟨1, by simp⟩
State after:
no goals

State before:
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
⊢ Exponential 0 1
Tactic:
simp
State after:
no goals

State before:
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
x : M
IH : ∃ y, Exponential x y
⊢ ∃ y, Exponential (x + 1) y
Tactic:
rcases IH with ⟨y, IH⟩
State after:
case intro
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
x y : M
IH : Exponential x y
⊢ ∃ y, Exponential (x + 1) y

State before:
case intro
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
x y : M
IH : Exponential x y
⊢ ∃ y, Exponential (x + 1) y
Tactic:
exact ⟨2 * y, IH.succ⟩
State after:
no goals