rw [clear_insertRat f hf]
case isTrue
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
h✝ :
  ({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits, assignments := f.assignments }.insertRatUnits
        (c.delete p).negate).snd =
    true
⊢ (({ clauses := f.clauses, rupUnits := f.rupUnits, ratUnits := f.ratUnits,
                  assignments := f.assignments }.insertRatUnits
              (c.delete p).negate).fst.clearRatUnits,
        true).fst =
    f
no goals