have h0 : insertUnit_invariant f.assignments f_readyForRupAdd.2.1 f.rupUnits f.assignments f_readyForRupAdd.2.1 := by
  intro i
  simp only [Fin.getElem_fin, ne_eq, true_and, Bool.not_eq_true, exists_and_right]
  apply Or.inl
  intro j
  simp only [f_readyForRupAdd.1, Array.size_toArray, List.length_nil] at j
  exact Fin.elim0 j
case intro
n : Nat
f : DefaultFormula n
f_readyForRupAdd : f.readyForRupAdd
c : DefaultClause n
p : PosFin n → Bool
pf : p ⊨ f
insertUnit_fold_success : (List.foldl insertUnit (f.rupUnits, f.assignments, false) c.negate).2.snd = true
false_imp : false = true → ∃ i, f.assignments[i.val] = both
i : PosFin n
hboth : (List.foldl insertUnit (f.rupUnits, f.assignments, false) c.negate).snd.fst[i.val] = both
i_in_bounds : i.val < f.assignments.size
⊢ p ⊨ c
case intro
n : Nat
f : DefaultFormula n
f_readyForRupAdd : f.readyForRupAdd
c : DefaultClause n
p : PosFin n → Bool
pf : p ⊨ f
insertUnit_fold_success : (List.foldl insertUnit (f.rupUnits, f.assignments, false) c.negate).2.snd = true
false_imp : false = true → ∃ i, f.assignments[i.val] = both
i : PosFin n
hboth : (List.foldl insertUnit (f.rupUnits, f.assignments, false) c.negate).snd.fst[i.val] = both
i_in_bounds : i.val < f.assignments.size
h0 : insertUnit_invariant f.assignments ⋯ f.rupUnits f.assignments ⋯
⊢ p ⊨ c