Abstract

The operads of little discs (and the equivalent operads of little cubes) were introduced in topology, in the works of Boardman–Vogt [7, 8] and May [47], for the recognition of iterated loop spaces. We refer to the paper [18], in the handbook of algebraic topology, for an account of these applications. We also refer to the literature for the general definition of an operad in a category and for the precise definition of the little discs operads, which we denote by D n throughout this chapter.