∀ {α : Type u_1} [inst : Field α] [inst_1 : LinearOrder α] [inst_2 : IsStrictOrderedRing α] {β : Type u_2}
  [inst_3 : Ring β] {abv : β → α} [inst_4 : IsAbsoluteValue abv] (x : β),
  CauSeq.Completion.ofRat (-x) = -CauSeq.Completion.ofRat x