ABSTRACT
This chapter first reviews the closely related notions of symmetric bimonoidal categories and bipermutative categories, followed by several important examples, including the indexing categories for Γ-categories and inverse K-theory. The second purpose of this chapter is to review Laplaza's Coherence Theorem for symmetric bimonoidal categories. Tight bipermutative categories, which have invertible factorization morphisms, are special cases of tight symmetric bimonoidal categories. Thus, Laplaza's Coherence Theorem also applies to tight bipermutative categories.
