next c _ =>
split
. rw [clear_insertRat f hf]
. let fc := (insertRatUnits f (negate (DefaultClause.delete c p))).1
  have fc_assignments_size : fc.assignments.size = n := by rw [insertRatUnits_preserves_assignments_size, hf.2]
  have insertRatUnits_rw : (insertRatUnits f (negate (DefaultClause.delete c p))).1 =
    ⟨(insertRatUnits f (negate (DefaultClause.delete c p))).1.clauses,
     (insertRatUnits f (negate (DefaultClause.delete c p))).1.rupUnits,
     (insertRatUnits f (negate (DefaultClause.delete c p))).1.ratUnits,
     (insertRatUnits f (negate (DefaultClause.delete c p))).1.assignments⟩ := rfl
  simp only [performRupCheck_preserves_clauses, performRupCheck_preserves_rupUnits, performRupCheck_preserves_ratUnits]
  rw [restoreAssignments_performRupCheck fc fc_assignments_size ratHint.2, ← insertRatUnits_rw,
    clear_insertRat f hf (negate (DefaultClause.delete c p))]
  split <;> rfl
case h_1
n : Nat
f : DefaultFormula n
hf : f.ratUnits = #[] ∧ f.assignments.size = n
p : Literal (PosFin n)
ratHint : Nat × Array Nat
x✝ : Option (DefaultClause n)
c✝ : DefaultClause n
heq✝ : f.clauses[ratHint.fst]! = some c✝
⊢ (if
          ({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                    assignments := f.assignments }.insertRatUnits
                (c✝.delete p).negate).snd =
            true then
        (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                    assignments := f.assignments }.insertRatUnits
                (c✝.delete p).negate).fst.clearRatUnits,
          true)
      else
        if
            (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                  assignments := f.assignments }.insertRatUnits
                              (c✝.delete p).negate).fst.performRupCheck
                        ratHint.snd).2.2.snd =
                true ∨
              (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                  assignments := f.assignments }.insertRatUnits
                              (c✝.delete p).negate).fst.performRupCheck
                        ratHint.snd).2.2.fst =
                false then
          ({
                clauses :=
                  (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                  assignments := f.assignments }.insertRatUnits
                              (c✝.delete p).negate).fst.performRupCheck
                        ratHint.snd).1.clauses,
                rupUnits :=
                  (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                  assignments := f.assignments }.insertRatUnits
                              (c✝.delete p).negate).fst.performRupCheck
                        ratHint.snd).1.rupUnits,
                ratUnits :=
                  (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                  assignments := f.assignments }.insertRatUnits
                              (c✝.delete p).negate).fst.performRupCheck
                        ratHint.snd).1.ratUnits,
                assignments :=
                  restoreAssignments
                    (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                    assignments := f.assignments }.insertRatUnits
                                (c✝.delete p).negate).fst.performRupCheck
                          ratHint.snd).1.assignments
                    (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                    assignments := f.assignments }.insertRatUnits
                                (c✝.delete p).negate).fst.performRupCheck
                          ratHint.snd).2.fst }.clearRatUnits,
            false)
        else
          ({
                clauses :=
                  (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                  assignments := f.assignments }.insertRatUnits
                              (c✝.delete p).negate).fst.performRupCheck
                        ratHint.snd).1.clauses,
                rupUnits :=
                  (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                  assignments := f.assignments }.insertRatUnits
                              (c✝.delete p).negate).fst.performRupCheck
                        ratHint.snd).1.rupUnits,
                ratUnits :=
                  (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                  assignments := f.assignments }.insertRatUnits
                              (c✝.delete p).negate).fst.performRupCheck
                        ratHint.snd).1.ratUnits,
                assignments :=
                  restoreAssignments
                    (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                    assignments := f.assignments }.insertRatUnits
                                (c✝.delete p).negate).fst.performRupCheck
                          ratHint.snd).1.assignments
                    (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                                    assignments := f.assignments }.insertRatUnits
                                (c✝.delete p).negate).fst.performRupCheck
                          ratHint.snd).2.fst }.clearRatUnits,
            true)).fst =
    f
no goals