Theorem: Unitization.norm_splitMul_snd_sq
File: Mathlib/Analysis/CstarAlgebra/Unitization.lean

Proof steps:
state_before: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ ‖((splitMul 𝕜 E) x).2‖ ^ 2 ≤ ‖((splitMul 𝕜 E) (x⋆ * x)).2‖
state_after: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ ‖((splitMul 𝕜 E) x).2‖ ≤ √‖((splitMul 𝕜 E) (x⋆ * x)).2‖
tactic: refine (Real.le_sqrt (norm_nonneg _) (norm_nonneg _)).mp ?_
state_before: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ ‖((splitMul 𝕜 E) x).2‖ ≤ √‖((splitMul 𝕜 E) (x⋆ * x)).2‖
state_after: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ ‖(algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd‖ ≤
    √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
tactic: simp only [Unitization.splitMul_apply]
state_before: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ ‖(algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd‖ ≤
    √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
state_after: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ sSup ((fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd) x_1‖) '' Metric.closedBall 0 1) ≤
    √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
tactic: rw [← sSup_closed_unit_ball_eq_norm]
state_before: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ sSup ((fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd) x_1‖) '' Metric.closedBall 0 1) ≤
    √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
state_after: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ ∀ b ∈ (fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd) x_1‖) '' Metric.closedBall 0 1,
    b ≤ √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
tactic: refine csSup_le ((Metric.nonempty_closedBall.2 zero_le_one).image _) ?_
state_before: 𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
⊢ ∀ b ∈ (fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd) x_1‖) '' Metric.closedBall 0 1,
    b ≤ √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
state_after: case intro.intro
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ (fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd) x_1‖) b ≤
    √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
tactic: rintro - ⟨b, hb, rfl⟩
state_before: case intro.intro
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ (fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd) x_1‖) b ≤
    √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
state_after: case intro.intro
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ ‖((algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd) b‖ ≤
    √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
tactic: simp only
state_before: case intro.intro
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ ‖((algebraMap 𝕜 (E →L[𝕜] E)) x.fst + (mul 𝕜 E) x.snd) b‖ ≤
    √‖(algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd‖
state_after: case intro.intro
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ ‖b⋆ * (x.fst⋆ • (x.fst • b + x.snd * b) + x.snd⋆ * (x.fst • b + x.snd * b))‖ ≤
    sSup
      ((fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd) x_1‖) '' Metric.closedBall 0 1)
tactic: rw [← Real.sqrt_sq (norm_nonneg _), Real.sqrt_le_sqrt_iff (norm_nonneg _), sq,
    ← CstarRing.norm_star_mul_self, ContinuousLinearMap.add_apply, star_add, mul_apply',
    Algebra.algebraMap_eq_smul_one, ContinuousLinearMap.smul_apply,
    ContinuousLinearMap.one_apply, star_mul, star_smul, add_mul, smul_mul_assoc, ← mul_smul_comm,
    mul_assoc, ← mul_add, ← sSup_closed_unit_ball_eq_norm]
state_before: case intro.intro
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ ‖b⋆ * (x.fst⋆ • (x.fst • b + x.snd * b) + x.snd⋆ * (x.fst • b + x.snd * b))‖ ≤
    sSup
      ((fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd) x_1‖) '' Metric.closedBall 0 1)
state_after: case intro.intro
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ ‖b⋆‖ * ‖x.fst⋆ • (x.fst • b + x.snd * b) + x.snd⋆ * (x.fst • b + x.snd * b)‖ ≤
    sSup
      ((fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd) x_1‖) '' Metric.closedBall 0 1)
tactic: refine (norm_mul_le _ _).trans ?_
state_before: case intro.intro
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ ‖b⋆‖ * ‖x.fst⋆ • (x.fst • b + x.snd * b) + x.snd⋆ * (x.fst • b + x.snd * b)‖ ≤
    sSup
      ((fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd) x_1‖) '' Metric.closedBall 0 1)
state_after: case intro.intro.calc_1
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ BddAbove
    ((fun x_1 => ‖((algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd) x_1‖) '' Metric.closedBall 0 1)

case intro.intro.calc_2
𝕜 : Type u_1
E : Type u_2
inst✝⁹ : DenselyNormedField 𝕜
inst✝⁸ : NonUnitalNormedRing E
inst✝⁷ : StarRing E
inst✝⁶ : CstarRing E
inst✝⁵ : NormedSpace 𝕜 E
inst✝⁴ : IsScalarTower 𝕜 E E
inst✝³ : SMulCommClass 𝕜 E E
inst✝² : StarRing 𝕜
inst✝¹ : CstarRing 𝕜
inst✝ : StarModule 𝕜 E
x : Unitization 𝕜 E
b : E
hb : b ∈ Metric.closedBall 0 1
⊢ ‖((algebraMap 𝕜 (E →L[𝕜] E)) (x⋆ * x).fst + (mul 𝕜 E) (x⋆ * x).snd) b‖ =
    ‖x.fst⋆ • (x.fst • b + x.snd * b) + x.snd⋆ * (x.fst • b + x.snd * b)‖
tactic: calc
    _ ≤ ‖star x.fst • (x.fst • b + x.snd * b) + star x.snd * (x.fst • b + x.snd * b)‖ := by
      nth_rewrite 2 [← one_mul ‖_ + _‖]
      gcongr
      exact (norm_star b).symm ▸ mem_closedBall_zero_iff.1 hb
    _ ≤ sSup (_ '' Metric.closedBall 0 1) := le_csSup ?_ ⟨b, hb, ?_⟩