Yoneda

------------- While we are asking terminological questions prompted by Mac Lane and Moerdijk, I'd like to know exactly what people mean by the Yoneda lemma. Does Yoneda include the fact that every presheaf is a canonical limit of representables? Does it include (as Johnstone has it, on _Topos Theory_ p.51) the claim that the Yoneda embedding to a presheaf category is left adjoint to the forgetful functor (i.e. the functor that forgets the action of arrows and only remembers the family of sets indexed over the objects of the domain category)? Colin McLarty ==============================================================================