congr! 1
σ : Formula → Formula
V : VarBoolAssignment
phi : Formula
phi_ih : evalPrime V (substPrime σ phi) ↔ evalPrime (fun H => decide (evalPrime V (σ H))) phi
⊢ ¬evalPrime V (substPrime σ phi) ↔ ¬evalPrime (fun H => decide (evalPrime V (σ H))) phi
no goals