A 2-dimensional torsion theory on symmetric monoidal categories

Abstract

In this paper we describe a homotopy torsion theory in the category of small symmetric monoidal categories. Thanks to the use of natural isomorphisms as basis for the nullhomotopy structure, this homotopy torsion theory enjoys some interesting 2-dimensional properties which may be the starting point for a definition of "2-dimensional torsion theory". As torsion objects we take symmetric 2-groups, thus generalising a known pointed torsion theory in the category of commutative monoids where abelian groups play the part of torsion objects. In the last part of the paper we carry out an analogous generalisation for the classical torsion theory in the category of abelian groups given by torsion and torsion-free groups.