Category Theory/(Co-)cones and (co-)limits

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Exercises

    1. Let π’Ÿ be a category such that every two objects of π’Ÿ have a product. Suppose further that π’ž is another category, and that T:π’žπ’Ÿ is a functor. Let Y be an object of π’Ÿ. Use the universal property of the product in order to show that there exists a functor SY:π’žπ’Ÿ that sends an object X of π’ž to the object T(X)×Y of π’Ÿ.
    2. Prove that any morphism g:YZ in π’Ÿ gives rise to a natural transformation SYSZ.
    3. Can we weaken the assumption that every two objects of π’Ÿ have a product? (Hint: Consider the image of the class function on objects associated to the functor T.)

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