intro assign _ idx hbound hmark
aig : AIG Nat
⊢ ∀ (assign : aig.CNFVar → Bool),
    CNF.eval assign [] = true →
      ∀ (idx : Nat) (hbound : idx < aig.decls.size),
        (mkArray aig.decls.size false)[idx] = true →
          ⟦{ aig := aig, ref := { gate := idx, hgate := hbound } }, projectLeftAssign assign⟧ =
            projectRightAssign assign idx hbound
aig : AIG Nat
assign : aig.CNFVar → Bool
_heval✝ : CNF.eval assign [] = true
idx : Nat
hbound : idx < aig.decls.size
hmark : (mkArray aig.decls.size false)[idx] = true
⊢ ⟦{ aig := aig, ref := { gate := idx, hgate := hbound } }, projectLeftAssign assign⟧ =
    projectRightAssign assign idx hbound