# “Change-of-base” between enriched categories

I would like to prove that a monoidal functor $$\Phi\colon \mathbf{V}\to \mathbf{V'}$$ induces a functor $$\Phi^\#\colon \mathbf{V}\text{-Cat}\to \mathbf{V'}\text{-Cat}$$

and in particular I would like to check that if $\Phi$ admits a left/right adjoint, then $\Phi^\#$ admits one too. The problem is that I'm stuck in finding the "right" definitions involved (especially that of monoidal functor); I have to silently suppose that $\Phi$ is strong (or "non-lax") monoidal, i.e. $\Phi(A\otimes B)\cong \Phi(A)\otimes '\Phi(B)$, $\Phi(I)\cong I'$ for all $A,B\in \mathbf{V}$ and the "initial" objects $I\in \mathbf V$, $I'\in \mathbf V'$. Such a restrictive assumption leaves me unsatisfied, but I'm not really keen on non-strict monoidal functors...

As a side question, it seems to me this is a well-established result in enriched category theory, but I'm not able to find a precise reference proving the result from the beginning: Kelly treats the result as a well known folklore, saying in the first pages of Basic concepts of ECT

[we do not] discuss the change of base-category given by a symmetric monoidal functor $\mathbf{V}\to \mathbf{V'}$ and the induced 2-functor $\mathbf{V}\text{-Cat}\to \mathbf{V'}\text{-Cat}, [...]$

and John Gray, in his article Closed Categories, Lax Limits and Homotopy Limits just gives a statement of the claim I would like to prove. Again, can you help me?

Thanks a lot.

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I believe you'll find the following article helpful:

Change of Base, Cauchy Completeness and Reversibility (pdf)

(In A. Labella & V. Schmitt, Theory and Applications of Categories, Vol. 10: 10, 2002, pp. 187–219.)

This linked article addresses much of what you're looking for, and includes references which may be of help to you. (E.g. G.M. Kelly, Basic Concepts of Enriched Category Theory, London Mathematical Society Lecture Notes Series 64, Cambridge University Press, 1982.)

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The first part of your first question (the existence of the $2$-functor $\Phi^\sharp$) can be found in Borceux's "Handbook of categorical algebra", vol 2, proposition 6.4.3. Notice that Borceux's monoidal functors are lax ones.

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Thanks, I already found it but I think it's nothing difficult to define $\Phi^\#$... the real problem by now seems to be "What is an adjunction between two 2-categories?" –  tetrapharmakon Jul 9 '11 at 13:47