Documentation

Mathlib.Condensed.Epi

Epimorphisms of condensed objects #

This file characterises epimorphisms of condensed sets and condensed R-modules for any ring R, as those morphisms which are objectwise surjective on Stonean (see CondensedSet.epi_iff_surjective_on_stonean and CondensedMod.epi_iff_surjective_on_stonean).

theorem CondensedSet.epi_iff_locallySurjective_on_compHaus {X : CondensedSet} {Y : CondensedSet} (f : X ⟶ Y) :
CategoryTheory.Epi f ↔ ∀ (S : CompHaus) (y : Y.val.obj (Opposite.op S)), ∃ (S' : CompHaus) (φ : S' ⟶ S) (_ : Function.Surjective ⇑φ) (x : X.val.obj (Opposite.op S')), f.val.app (Opposite.op S') x = Y.val.map (Opposite.op φ) y
theorem CondensedMod.epi_iff_locallySurjective_on_compHaus (R : Type (u + 1)) [Ring R] {X : CondensedMod R} {Y : CondensedMod R} (f : X ⟶ Y) :
CategoryTheory.Epi f ↔ ∀ (S : CompHaus) (y : ↑(Y.val.obj (Opposite.op S))), ∃ (S' : CompHaus) (φ : S' ⟶ S) (_ : Function.Surjective ⇑φ) (x : ↑(X.val.obj (Opposite.op S'))), (f.val.app (Opposite.op S')) x = (Y.val.map (Opposite.op φ)) y
theorem CondensedMod.epi_iff_surjective_on_stonean (R : Type (u + 1)) [Ring R] {X : CondensedMod R} {Y : CondensedMod R} (f : X ⟶ Y) :
CategoryTheory.Epi f ↔ ∀ (S : Stonean), Function.Surjective ⇑(f.val.app (Opposite.op S.compHaus))