678 

   678 

   679 %We will aim for a little bit more generality than we need and not assume that the objects

   679 %We will aim for a little bit more generality than we need and not assume that the objects

   680 %of our auxiliary category are sets with extra structure.

   680 %of our auxiliary category are sets with extra structure.

   681 First we must specify requirements for the auxiliary category.

   681 First we must specify requirements for the auxiliary category.

   682 It should have a {\it distributive monoidal structure} in the sense of 

   682 It should have a {\it distributive monoidal structure} in the sense of 

   684 This means that there is a monoidal structure $\otimes$ and also coproduct $\oplus$,

   684 This means that there is a monoidal structure $\otimes$ and also coproduct $\oplus$,

   685 and these two structures interact in the appropriate way.

   685 and these two structures interact in the appropriate way.

   686 Examples include 

   686 Examples include 

   687 \begin{itemize}

   687 \begin{itemize}

   688 \item vector spaces (or $R$-modules or chain complexes) with tensor product and direct sum; and

   688 \item vector spaces (or $R$-modules or chain complexes) with tensor product and direct sum; and