exact isProper_append (isProper_ofDerivation ⟨bp, H.1⟩) (isProper_ofDerivation ⟨bq, H.2⟩)
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 : List (SyntacticFormula L)
p q : SyntacticFormula L
bp : Derivation (p :: Γ)
bq : Derivation (q :: Γ)
H✝ : CutFree (bp.and bq)
H : CutFree bp ∧ CutFree bq
⊢ (ofDerivation ⟨bp, ⋯⟩ ++ ofDerivation ⟨bq, ⋯⟩).isProper = true
no goals