sheafification — Mathlib

English

The operation of applying sheafification twice yields a sheaf; in particular P⁺⁺ is a sheaf when P is separated.

Русский

Производное шеффайикации 2 раза дает шефф: P⁺⁺ является шефом если P разделим.

LaTeX

$$Presheaf.IsSheaf J (J.plusObj (J.plusObj P))$$

Lean4

/-- The sheafification of a presheaf `P`, as a functor.
*NOTE:* Additional hypotheses are needed to obtain a proof that this is a sheaf! -/
noncomputable def sheafification : (Cᵒᵖ ⥤ D) ⥤ Cᵒᵖ ⥤ D :=
  J.plusFunctor D ⋙ J.plusFunctor D

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