There is a strict 2-functor (()−Cat=()∗):MONCAT→CAT:V↦(V−Cat=V∗)
between (the indicated strict 2-categories);
see CC II.6.3, also RE2C ¶1.3.2;
the notation V−Cat is now more standard, see e.g. BCECT,
but CC uses the briefer notations V∗, Φ∗ and η∗ for the effect on monoidal categories, monoidal functors and monoidal natural transformations.
(Also, CC calls 2-categories “hypercategories”, a term no longer used for 2-categories.)
(The ()∗ notation) is consistent with (other usages of ()∗):
if we severely overload (the symbol X) so that it stands for (a) a V-category and (b) that V-category's set (or class) of objects, with (c) −X− denoting X's hom-function,
then (the hom-function of XΦ∗) is defined as:
−(XΦ∗)−:X×X−X−→Vϕ→V′:⟨x,y⟩↦xXyϕ=x(XΦ∗)y.
For its brevity we adopt this notation for the effects of (()−Cat=()∗) on monoidal functors and monoidal natural transformations: thus F∗ and η∗,
while using the notation V−Cat for the effect on monoidal categories.
[the image under the 2-functor \big( ()\mathord-\Cat = ()_\ast \big)]
of (the above adjunction in the 2-category \MONCAT)
is (an adjunction in the 2-category \CAT): \boxed{\begin{array}{} \functionh & \in & \mkern1em \hom \setX {\Set\mathord-\Cat} {\objectA \functorU_\ast} & \mkern2em \smash{\Rule {2px} {2ex} {11ex}} \mkern1em & && \langle \Set,\times,1 \rangle\mathord-\Cat && \xrightarrow{\mkern3em} && \langle \Set,\times,1 \rangle\mathord-\Cat && \xrightarrow{\mkern3em} && \langle \Set,\times,1 \rangle\mathord-\Cat \\ && \wr\Vert && & \llap\setX \nearrow & \llap\functionk \Big\Downarrow & \searrow \rlap{\functorF_\ast} & \Big\Downarrow \rlap{\eta_\ast} & \nearrow \rlap{\functorU_\ast} & \llap\Vert \Big\Downarrow \rlap{\epsilon_\ast} & \searrow \rlap{\functorF_\ast} & \Big\Downarrow \rlap{\eta_\ast} & \nearrow \rlap{\functorU_\ast = \langle \functoru,\tilde\functoru,\functoru^\circ \rangle _\ast} \\ \functionk & \in & \mkern.6em \hom {\setX \functorF_\ast} {\cattwo\mathord-\Cat} \objectA && \catI && \xrightarrow[\textstyle \objectA]{\smash{\mkern3em}} && \langle \cattwo,\land,\top \rangle\mathord-\Cat && \xrightarrow[\mkern3em]{\smash{}} && \langle \cattwo,\land,\top \rangle\mathord-\Cat \\ \end{array}} (The monoidal structures \functoru^\circ, \tilde\functoru, \functorf^\circ, and \tilde\functorf) combine with (the functors \functoru and \functorf themselves)
to produce (\functorU_\ast and \functorF_\ast):
the units (CC I(6.3)) and compositions (CC II(6.1)) of (\objectA\functorU_\ast and \objectX\functorF_\ast) are defined by: \mkern-3em \begin{array}{} && && && && & \hom \objecta {(\objectA\functorU_\ast)} \objectb \times \hom \objectb {(\objectA\functorU_\ast)} \objectc &&&& &&&& &&&& & \hom \objectx {(\objectX\functorF_\ast)} \objecty \land \hom \objecty {(\objectX\functorF_\ast)} \objectz \\ && && && && & \Vert &&&& &&&& &&&& & \Vert \\ && 1 & = & 1 && && & (\hom \objecta \objectA \objectb)\functoru \times (\hom \objectb \objectA \objectc)\functoru &&&&&& \top & = & \top &&&&& (\hom \objectx \objectX \objecty)\functorf \land (\hom \objecty \objectX \objectz)\functorf \\ && \llap{\wr\Vert} \big\downarrow & \functoru^\circ & \llap{\wr\Vert} \big\downarrow & && && \llap{\wr\Vert} \big\downarrow \rlap{\langle \hom \objecta \objectA \objectb, \hom \objectb \objectA \objectc \rangle \tilde\functoru} &&&& && \llap{\Vert} \big\downarrow & \functorf^\circ & \llap{\Vert} \big\downarrow &&&&& \llap{\Vert} \big\downarrow \rlap{\langle \hom \objectx \objectX \objecty, \hom \objecty \objectX \objectz \rangle \tilde\functorf} \\ \top & \mathop\mapsto\limits^\functoru& \top\functoru & = & \hom \top \cattwo \top &&& \hom \objecta \objectA \objectb \land \hom \objectb \objectA \objectc & \mathop\mapsto\limits^\functoru & \big( \hom \objecta \objectA \objectb \land \hom \objectb \objectA \objectc \big)\functoru &&&& 1 & \mathop\mapsto\limits^\functorf & 1\functorf & = & 1\cdot\top &&& \hom \objectx \objectX \objecty \times \hom \objecty \objectX \objectz & \mathop\mapsto\limits^\functorf & \big( \hom \objectx \objectX \objecty \times \hom \objecty \objectX \objectz \big)\functorf \\ \llap{\text{refl}} \big\downarrow & \mathop\mapsto\limits^\functoru & \llap{\text{refl}\functoru} \big\downarrow & = & \big\downarrow \rlap{\hom \top \cattwo {\text{refl}}} &&& \llap{\text{trans}} \big\downarrow & \mathop\mapsto\limits^\functoru & \llap{\text{trans}\functoru} \big\downarrow &&&& \llap{\objectx\arrowj} \big\downarrow & \mathop\mapsto\limits^\functorf & \llap{\objectx\arrowj\functorf} \big\downarrow & = & \big\downarrow \rlap{(\objectx\arrowj)\cdot\top} &&& \llap{\Mforcomp} \big\downarrow & \mathop\mapsto\limits^\functorf & \big\downarrow \rlap {\Mforcomp\functorf} \\ \hom \objecta \objectA \objecta & \mathop\mapsto\limits^\functoru & \hom \objecta \objectA \objecta \functoru & = & \hom \top \cattwo {\hom \objecta \objectA \objecta} &&& \hom \objecta \objectA \objectc & \mathop\mapsto\limits^\functoru & \hom \objecta \objectA \objectc \functoru &&&& \hom \objectx \objectX \objectx & \mathop\mapsto\limits^\functorf & \hom \objectx \objectX \objectx \functorf & = & \hom \objectx \objectX \objectx \cdot\top &&& \hom \objectx \objectX \objectz & \mathop\mapsto\limits^\functorf & \hom \objectx \objectX \objectz \functorf \\ && \Vert && && && & \Vert &&&& && \Vert && &&&& & \Vert \\ && {} \rlap{\mkern-2em \hom \objecta {(\objectA\functorU_\ast)} \objecta} && && && & {} \rlap{\mkern-2em \hom \objecta {(\objectA\functorU_\ast)} \objectc} &&&& && \hom \objectx {(\objectX\functorF_\ast)} \objectx && &&&& & \hom \objectx {(\objectX\functorF_\ast)} \objectz \\ \end{array}
Here of course (\text{refl} and \text{trans}) are the implementations in (\cattwo-category theory)
of (the reflexive and transitive axioms for preorders);
in (the notation of CC) they would be denoted \objecta\arrowj and (\Mforcomp = \Mforcomp^\objectb_{\objecta\objectc}) respectively.
References
CC, Eilenberg and Kelly, “Closed Categories”, 1966RE2C, Kelly and Street, “Review of the Elements of 2-Categories”, 1974
BCECT, Kelly, Basic Concepts of Enriched Category Theory, 1982/2005
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