nLab Gamma-set

Let Γ op\Gamma^{op} (see Segal's category) be the skeleton of the category of finite pointed sets. We write n̲\underline{n} for the finite pointed set with nn non-basepoint elements. Then a Γ\Gamma-set is a functor X:Γ opSetX\colon \Gamma^{op}\to Set.

The topos Set Γ op\Set^{\Gamma^{op}} of Γ\Gamma-sets is the classifying topos for pointed objects (MO question). For more on this see also at classifying topos for the theory of objects.

Related nnLab entries include Gamma-space, Segal's category.

Created on November 5, 2016 at 14:56:15. See the history of this page for a list of all contributions to it.