simp[isProper, sequents_cons, List.mem_cons_cons, mem_ofDerivation, ss]
μ : Type ?u.910235
L : Language
inst✝⁶ : (k : ℕ) → DecidableEq (L.Func k)
inst✝⁵ : (k : ℕ) → DecidableEq (L.Rel k)
inst✝⁴ : (k : ℕ) → Primcodable (L.Func k)
inst✝³ : (k : ℕ) → Primcodable (L.Rel k)
inst✝² : UniformlyPrimcodable L.Func
inst✝¹ : UniformlyPrimcodable L.Rel
inst✝ : Primcodable μ
Γ' Γ : Sequent L
b : Derivation Γ
ss : Γ ⊆ Γ'
H : CutFree (b.wk ss)
⊢ isProper ((Code.wk Γ, Γ') :: ofDerivation ⟨b, ⋯⟩) = true
μ : Type ?u.910235
L : Language
inst✝⁶ : (k : ℕ) → DecidableEq (L.Func k)
inst✝⁵ : (k : ℕ) → DecidableEq (L.Rel k)
inst✝⁴ : (k : ℕ) → Primcodable (L.Func k)
inst✝³ : (k : ℕ) → Primcodable (L.Rel k)
inst✝² : UniformlyPrimcodable L.Func
inst✝¹ : UniformlyPrimcodable L.Rel
inst✝ : Primcodable μ
Γ' Γ : Sequent L
b : Derivation Γ
ss : Γ ⊆ Γ'
H : CutFree (b.wk ss)
⊢ (ofDerivation ⟨b, ⋯⟩).isProper = true