apply k_ne_zero
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
acc : Array Assignment × List (Literal (PosFin n)) × Bool × Bool
hsize : acc.fst.size = n
l : Literal (PosFin n)
ih : f.derivedLits_invariant f_assignments_size acc.fst hsize acc.snd.fst
h : ¬hasAssignment l.snd acc.fst[l.fst.val]! = true
hsize'✝ : (acc.fst.modify l.fst.val (addAssignment l.snd)).size = n :=
  Eq.mpr (id (congrArg (fun _a => _a = n) Array.modify_preserves_size)) hsize
i : Fin n
i_in_bounds : ↑i < acc.fst.size
l_in_bounds : l.fst.val < acc.fst.size
h1 : acc.fst[↑i] = f.assignments[↑i]
h2 : ∀ (l : Literal (PosFin n)), l ∈ acc.snd.fst → l.fst.val ≠ ↑i
l_eq_i : l.fst.val = ↑i
zero_lt_length_list : 0 < (l :: acc.snd.fst).length
k : Fin (l :: acc.snd.fst).length
k_ne_zero : ¬k = 0
k_eq_zero : ↑k = 0
⊢ False
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
acc : Array Assignment × List (Literal (PosFin n)) × Bool × Bool
hsize : acc.fst.size = n
l : Literal (PosFin n)
ih : f.derivedLits_invariant f_assignments_size acc.fst hsize acc.snd.fst
h : ¬hasAssignment l.snd acc.fst[l.fst.val]! = true
hsize'✝ : (acc.fst.modify l.fst.val (addAssignment l.snd)).size = n :=
  Eq.mpr (id (congrArg (fun _a => _a = n) Array.modify_preserves_size)) hsize
i : Fin n
i_in_bounds : ↑i < acc.fst.size
l_in_bounds : l.fst.val < acc.fst.size
h1 : acc.fst[↑i] = f.assignments[↑i]
h2 : ∀ (l : Literal (PosFin n)), l ∈ acc.snd.fst → l.fst.val ≠ ↑i
l_eq_i : l.fst.val = ↑i
zero_lt_length_list : 0 < (l :: acc.snd.fst).length
k : Fin (l :: acc.snd.fst).length
k_ne_zero : ¬k = 0
k_eq_zero : ↑k = 0
⊢ k = 0