| import Mathlib | |
| open CategoryTheory | |
| def RingCat.units : RingCat.{u} ⥤ Grp.{u} where | |
| obj R := .of Rˣ | |
| map f := Grp.ofHom (Units.map f.hom) | |
| theorem exists_leftAdjoint_unitFunctor : | |
| ∃ (left : Grp.{u} ⥤ RingCat.{u}), Nonempty (left ⊣ RingCat.units.{u}) := by | |
| sorry | |