English
Several lemmas state the behavior of overEquiv with respect to top and pullback/pushforward operations.
Русский
Несколько лемм описывают поведение overEquiv относительно верхнего севея и операций подстановки/перемещения.
LaTeX
$$$$ \text{(typical identities involving top, pullback, pushforward and forgetful functor)} $$$$
Lean4
@[simp]
theorem overEquiv_top {X : C} (Y : Over X) : overEquiv Y ⊤ = ⊤ :=
by
ext Z g
simp only [top_apply, iff_true]
dsimp [overEquiv, Presieve.functorPushforward]
exact ⟨Y, 𝟙 Y, g, by simp, by simp⟩