desc_eq — Mathlib

English

The descent morphism of a family of arrows f,g into T is the sum of the left and right projections composed with f and g.

Русский

Унисальная десктораяция: descent f g = fst ∘ f + snd ∘ g.

LaTeX

$$$\operatorname{biproduct.desc} f g = \operatorname{biprod.fst} \circ f + \operatorname{biprod.snd} \circ g$$$

Lean4

theorem desc_eq {T : C} {f : X ⟶ T} {g : Y ⟶ T} : biprod.desc f g = biprod.fst ≫ f + biprod.snd ≫ g := by ext <;> simp

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