LeanAide GPT-4 documentation

Module: Mathlib.Topology.Sheaves.Skyscraper


StalkSkyscraperPresheafAdjunctionAuxs.fromStalk_to_skyscraper

theorem StalkSkyscraperPresheafAdjunctionAuxs.fromStalk_to_skyscraper : โˆ€ {X : TopCat} (pโ‚€ : โ†‘X) [inst : (U : TopologicalSpace.Opens โ†‘X) โ†’ Decidable (pโ‚€ โˆˆ U)] {C : Type v} [inst_1 : CategoryTheory.Category.{u, v} C] [inst_2 : CategoryTheory.Limits.HasTerminal C] [inst_3 : CategoryTheory.Limits.HasColimits C] {๐“• : TopCat.Presheaf C X} {c : C} (f : ๐“•.stalk pโ‚€ โŸถ c), StalkSkyscraperPresheafAdjunctionAuxs.fromStalk pโ‚€ (StalkSkyscraperPresheafAdjunctionAuxs.toSkyscraperPresheaf pโ‚€ f) = f

This theorem states that for a given topological space `X`, a point `pโ‚€` in `X`, a category `C` with terminal objects and colimits, a presheaf `๐“•` of `C` on `X`, and a morphism `f` from the stalk of the presheaf at the point `pโ‚€` to an object `c` in `C`, the composition of the morphism `f` with the function `fromStalk` applied to the result of `toSkyscraperPresheaf` applied to `f` is equal to `f` itself. Essentially, it expresses a kind of round-trip property: if you map a stalked presheaf to a 'skyscraper presheaf' and then map it back again, you get the original presheaf.

More concisely: For any topological space X, presheaf ๐“• on X, point p0 in X, object c in the category C with terminal objects and colimits, and morphism f from the stalk of ๐“• at p0 to c, the diagram commutes: fromStalk (toSkyscraperPresheaf f) = f.