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  1. import category_theory.universal.limits
  2. import category_theory.functor_category
  3.  
  4. universes u v
  5.  
  6. namespace category_theory.universal
  7. open category_theory
  8.  
  9. variables {C : Type u} [𝒞 : category.{u v} C] [has_limits.{u v} C]
  10. include 𝒞
  11.  
  12. def lim {J : Type v} [small_category J] : (J ↝ C) ↝ C :=
  13. { obj := limit,
  14. map' := λ F F' t, (limit.universal_property F').lift $
  15. { X := limit F, π := λ j, limit.π F j ≫ t.app j },
  16. map_id' := assume F,
  17. by apply limit.hom_characterisation; simp [limit.π, -limit.cone_π],
  18. map_comp' := assume F F' F'' t t', begin
  19. apply limit.hom_characterisation; simp [limit.π, -limit.cone_π],
  20. intro j, rw [←category.assoc, is_limit.fac], simp
  21. end }
  22.  
  23. end category_theory.universal
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