This entry is about expansion in shape theory rather than in cosmology (or elsewhere, like in theory of fluids).

Let 𝒯\mathcal{T} be a category, 𝒫𝒯\mathcal{P}\subset\mathcal{T} a subcategory and XX an object in 𝒯\mathcal{T}. The canonical embedding 𝒯pro𝒯\mathcal{T}\to pro\mathcal{T} into the pro-category may be considered as an identification. A 𝒯\mathcal{T}-expansion (or simply an expansion) of XX is an initial object in the coslice category X/pro𝒯X/pro\mathcal{T}. A 𝒯\mathcal{T}-expansion is a 𝒫\mathcal{P}-expansion if it is a morphism in 𝒫\mathcal{P}.

Created on September 16, 2017 at 13:47:11. See the history of this page for a list of all contributions to it.