apply Exists.intro hsize'
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
rupHints : Array Nat
i : Fin rupHints.size
acc : Array Assignment × List (Literal (PosFin n)) × Bool × Bool
hsize : acc.fst.size = n
ih : f.derivedLits_invariant f_assignments_size acc.fst hsize acc.snd.fst
hsize' : (confirmRupHint f.clauses acc rupHints[i]).fst.size = n
⊢ let rupHint_res := confirmRupHint f.clauses acc rupHints[i];
  ∃ hsize, f.derivedLits_invariant f_assignments_size rupHint_res.fst hsize rupHint_res.snd.fst
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
rupHints : Array Nat
i : Fin rupHints.size
acc : Array Assignment × List (Literal (PosFin n)) × Bool × Bool
hsize : acc.fst.size = n
ih : f.derivedLits_invariant f_assignments_size acc.fst hsize acc.snd.fst
hsize' : (confirmRupHint f.clauses acc rupHints[i]).fst.size = n
⊢ f.derivedLits_invariant f_assignments_size (confirmRupHint f.clauses acc rupHints[i]).fst hsize'
    (confirmRupHint f.clauses acc rupHints[i]).snd.fst