n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
h₁ : n ≤ sInf {m | p (m - n)}
⊢ sInf {m | p m} + n = sInf {m | p (m - n)}

case h₁
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
⊢ n ≤ sInf {m | p (m - n)}
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
⊢ sInf {m | p m} + n = sInf {m | p (m - n)}
suffices h₁ : n ≤ sInf {m | p (m - n)}
case h.e'_2.h.e'_5.h.e'_3.h.e'_2.h.h.e'_1
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
h₁ : n ≤ sInf {m | p (m - n)}
x✝ : ℕ
⊢ x✝ = x✝ + n - n

case h₁
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
⊢ n ≤ sInf {m | p (m - n)}
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
h₁ : n ≤ sInf {m | p (m - n)}
⊢ sInf {m | p m} + n = sInf {m | p (m - n)}

case h₁
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
⊢ n ≤ sInf {m | p (m - n)}
convert sInf_add h₁
case h₁.intro
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
m : ℕ
hm : m ∈ {m | p m}
⊢ n ≤ sInf {m | p (m - n)}
case h₁
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
⊢ n ≤ sInf {m | p (m - n)}
obtain ⟨m, hm⟩ := nonempty_of_pos_sInf h
case h₁.intro.refine'_1
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
m : ℕ
hm : m ∈ {m | p m}
⊢ m + n ∈ {m | p (m - n)}

case h₁.intro.refine'_2
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
m : ℕ
hm : m ∈ {m | p m}
b : ℕ
hb : b ∈ {m | p (m - n)}
hbn : b < n
⊢ b - n ∈ {m | p m}
case h₁.intro
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
m : ℕ
hm : m ∈ {m | p m}
⊢ n ≤ sInf {m | p (m - n)}
refine'
  le_csInf ⟨m + n, _⟩ fun b hb ↦
    le_of_not_lt fun hbn ↦
      ne_of_mem_of_not_mem _ (not_mem_of_lt_sInf h) (tsub_eq_zero_of_le hbn.le)
no goals
case h.e'_2.h.e'_5.h.e'_3.h.e'_2.h.h.e'_1
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
h₁ : n ≤ sInf {m | p (m - n)}
x✝ : ℕ
⊢ x✝ = x✝ + n - n
simp_rw [add_tsub_cancel_right]
case h₁.intro.refine'_1
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
m : ℕ
hm : m ∈ {m | p m}
⊢ p (m + n - n)
case h₁.intro.refine'_1
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
m : ℕ
hm : m ∈ {m | p m}
⊢ m + n ∈ {m | p (m - n)}
dsimp
no goals
case h₁.intro.refine'_1
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
m : ℕ
hm : m ∈ {m | p m}
⊢ p (m + n - n)
rwa [add_tsub_cancel_right]
no goals
case h₁.intro.refine'_2
n : ℕ
p : ℕ → Prop
h : 0 < sInf {m | p m}
m : ℕ
hm : m ∈ {m | p m}
b : ℕ
hb : b ∈ {m | p (m - n)}
hbn : b < n
⊢ b - n ∈ {m | p m}
exact hb