The Grothendieck Construction of Bipermutative-Indexed Categories and Pseudo Symmetric Inverse K-Theory

Abstract

The Grothendieck construction is a fundamental link between indexed categories and opfibrations. This work is a detailed study of the Grothendieck construction over a small tight bipermutative category in the context of Cat-enriched multicategories, with applications to inverse K-theory and pseudo symmetric E-infinity-algebras. The ordinary Grothendieck construction over a small category C is a 2-equivalence that sends a C-indexed category to an opfibration over C. We show that the Grothendieck construction over a small tight bipermutative category D is a pseudo symmetric Cat-multifunctor that is generally not a Cat-multifunctor in the symmetric sense. When the projection to D is taken into account, we prove that the Grothendieck construction over D lifts to a non-symmetric Cat-multiequivalence whose codomain is a non-symmetric Cat-multicategory with small permutative opfibrations over D as objects. As applications we show that inverse K-theory, from Gamma-categories to small permutative categories, is a pseudo symmetric Cat-multifunctor but not a Cat-multifunctor in the symmetric sense. It follows that inverse K-theory preserves algebraic structures parametrized by non-symmetric and pseudo symmetric Cat-multifunctors but not Cat-multifunctors in general. As a special case, we observe that inverse K-theory sends pseudo symmetric E-infinity-algebras in Gamma-categories to pseudo symmetric E-infinity-algebras in small permutative categories.