-- Mathlib/NumberTheory/NumberField/CanonicalEmbedding/ConvexBody.lean
theorem convexBodyLT'_mem {x : K} :
    mixedEmbedding K x ∈ convexBodyLT' K f w₀ ↔
      (∀ w : InfinitePlace K, w ≠ w₀ → w x < f w) ∧
      |(w₀.val.embedding x).re| < 1 ∧ |(w₀.val.embedding x).im| < (f w₀ : ℝ) ^ 2

Proof state:
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
⊢ ((∀ (a : InfinitePlace K), a.IsReal → a x < ↑(f a)) ∧
      ∀ (a : InfinitePlace K) (b : a.IsComplex),
        a.embedding x ∈ if ⟨a, b⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f a) ^ 2} else ball 0 ↑(f a)) ↔
    (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
      |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2

Tactic:
refine ⟨fun ⟨h₁, h₂⟩ ↦ ⟨fun w h_ne ↦ ?_, ?_⟩, fun ⟨h₁, h₂⟩ ↦ ⟨fun w hw ↦ ?_, fun w hw ↦ ?_⟩⟩

Result:
case refine_1
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (a : InfinitePlace K), a.IsReal → a x < ↑(f a)) ∧
    ∀ (a : InfinitePlace K) (b : a.IsComplex),
      a.embedding x ∈ if ⟨a, b⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f a) ^ 2} else ball 0 ↑(f a)
h₁ : ∀ (a : InfinitePlace K), a.IsReal → a x < ↑(f a)
h₂ :
  ∀ (a : InfinitePlace K) (b : a.IsComplex),
    a.embedding x ∈ if ⟨a, b⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f a) ^ 2} else ball 0 ↑(f a)
w : InfinitePlace K
h_ne : w ≠ ↑w₀
⊢ w x < ↑(f w)

case refine_2
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (a : InfinitePlace K), a.IsReal → a x < ↑(f a)) ∧
    ∀ (a : InfinitePlace K) (b : a.IsComplex),
      a.embedding x ∈ if ⟨a, b⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f a) ^ 2} else ball 0 ↑(f a)
h₁ : ∀ (a : InfinitePlace K), a.IsReal → a x < ↑(f a)
h₂ :
  ∀ (a : InfinitePlace K) (b : a.IsComplex),
    a.embedding x ∈ if ⟨a, b⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f a) ^ 2} else ball 0 ↑(f a)
⊢ |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2

case refine_3
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsReal
⊢ w x < ↑(f w)

case refine_4
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsComplex
⊢ w.embedding x ∈ if ⟨w, hw⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f w) ^ 2} else ball 0 ↑(f w)

Proof state:
case refine_3
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsReal
⊢ w x < ↑(f w)

Tactic:
exact h₁ w (ne_of_isReal_isComplex hw w₀.prop)

Result:
no goals

Proof state:
case neg
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsComplex
h_ne : ¬w = ↑w₀
⊢ w.embedding x ∈ if ⟨w, hw⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f w) ^ 2} else ball 0 ↑(f w)

Tactic:
rw [if_neg (by exact Subtype.coe_ne_coe.1 h_ne)]

Result:
case neg
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsComplex
h_ne : ¬w = ↑w₀
⊢ w.embedding x ∈ ball 0 ↑(f w)

Proof state:
case pos
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsComplex
h_ne : w = ↑w₀
⊢ w.embedding x ∈ if ⟨w, hw⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f w) ^ 2} else ball 0 ↑(f w)

Tactic:
simpa [h_ne]

Result:
no goals

Proof state:
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (a : InfinitePlace K), a.IsReal → a x < ↑(f a)) ∧
    ∀ (a : InfinitePlace K) (b : a.IsComplex),
      a.embedding x ∈ if ⟨a, b⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f a) ^ 2} else ball 0 ↑(f a)
h₁ : ∀ (a : InfinitePlace K), a.IsReal → a x < ↑(f a)
w : InfinitePlace K
h_ne : w ≠ ↑w₀
hw : ¬w.IsReal
h₂ : if ⟨w, ⋯⟩ = w₀ then |(w.embedding x).re| < 1 ∧ |(w.embedding x).im| < ↑(f w) ^ 2 else w x < ↑(f w)
⊢ ¬⟨w, ⋯⟩ = w₀

Tactic:
exact Subtype.coe_ne_coe.1 h_ne

Result:
no goals

Proof state:
case refine_4
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsComplex
⊢ w.embedding x ∈ if ⟨w, hw⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f w) ^ 2} else ball 0 ↑(f w)

Tactic:
by_cases h_ne : w = w₀

Result:
case pos
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsComplex
h_ne : w = ↑w₀
⊢ w.embedding x ∈ if ⟨w, hw⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f w) ^ 2} else ball 0 ↑(f w)

case neg
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsComplex
h_ne : ¬w = ↑w₀
⊢ w.embedding x ∈ if ⟨w, hw⟩ = w₀ then {x | |x.re| < 1 ∧ |x.im| < ↑(f w) ^ 2} else ball 0 ↑(f w)

Proof state:
case neg
K : Type u_1
inst✝ : Field K
f : InfinitePlace K → ℝ≥0
w₀ : { w // w.IsComplex }
x : K
x✝ :
  (∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)) ∧
    |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
h₁ : ∀ (w : InfinitePlace K), w ≠ ↑w₀ → w x < ↑(f w)
h₂ : |((↑w₀).embedding x).re| < 1 ∧ |((↑w₀).embedding x).im| < ↑(f ↑w₀) ^ 2
w : InfinitePlace K
hw : w.IsComplex
h_ne : ¬w = ↑w₀
⊢ w x < ↑(f w)

Tactic:
exact h₁ w h_ne

Result:
no goals