simp only [evalPrimeFfToNot]
case h2.h3
P : Formula
h1 : ∀ (V : VarBoolAssignment), evalPrime V P
V : VarBoolAssignment
⊢ P = evalPrimeFfToNot V P
case h2.h3
P : Formula
h1 : ∀ (V : VarBoolAssignment), evalPrime V P
V : VarBoolAssignment
⊢ P = if evalPrime V P then P else P.not_