In this paper, we state and prove precise theorems on the classification of
the category of (braided) categorical groups and their (braided) monoidal
functors, and some applications obtained from the basic studies on monoidal
functors between categorical groups.
The notion of Ann-categories is a categorification of the ring structure.
Regular Ann-categories were classified by Shukla algebraic cohomology. In this
article, we state and prove the precise theorem on classification for the
general case due to Mac Lane cohomology for rings. And an application for
classification problem of ring extensions is also introduced.
Dual monoidal category $\mathcal C^\ast$ of a monoidal functor $F:\mathcal
C\to \mathcal V$ has been constructed by S. Majid. In this paper, we extend the
construction of dual structures for an Ann-functor $F:\mathcal B\to \mathcal
A$. In particular, when $F=id_{\mathcal A}$, then the dual category $\mathcal
A^{\ast}$ is indeed the center of $\mathcal A$ and this is a braided
Ann-category.
A braided Ann-category $\A$ is an Ann-category $\A$ together with the
braiding $c$ such that $(\A, \otimes, a, c, (I,l,r))$ is a braided tensor
category, and $c$ is compatible with the distributivity constraints. The paper
shows the dependence of the left (or right) distributivity constraint on other
axioms. Hence, the paper shows the relation to the concepts of {\it
distributivity category} due to M. L. Laplaza and {\it ring-like category} due
to A. Frohlich and C.T.C Wall.