exact psi_ih V h1_right
case a.h'.a
D : Type
I : Interpretation D
M : MetaValuation D
E : Env
σ : Instantiation
σ' : VarName → VarName
τ : MetaInstantiation
h2 : ↑σ ∘ σ' = id ∧ σ' ∘ ↑σ = id
phi psi : Formula
phi_ih :
  ∀ (V : Valuation D),
    IsMetaVarOrAllDefInEnv E phi →
      (Holds D I (V ∘ ↑σ) (fun X' V' => Holds D I (V' ∘ σ') M E (τ X')) E phi ↔ Holds D I V M E (sub σ τ phi))
psi_ih :
  ∀ (V : Valuation D),
    IsMetaVarOrAllDefInEnv E psi →
      (Holds D I (V ∘ ↑σ) (fun X' V' => Holds D I (V' ∘ σ') M E (τ X')) E psi ↔ Holds D I V M E (sub σ τ psi))
V : Valuation D
h1_left : IsMetaVarOrAllDefInEnv E phi
h1_right : IsMetaVarOrAllDefInEnv E psi
a✝ : Holds D I V M E (sub σ τ phi)
⊢ Holds D I (V ∘ ↑σ) (fun X' V' => Holds D I (V' ∘ σ') M E (τ X')) E psi ↔ Holds D I V M E (sub σ τ psi)
no goals