English
Final restatement: preserves limits with whisker equivalence for an initial F and composed G.
Русский
Финальное переформулирование: сохранение пределов с эквивалентностью whisker для начального F и композиции G.
LaTeX
$$$$ \text{preservesLimit_of_comp } \Rightarrow \text{PreservesLimit } G H $$$$
Lean4
theorem preservesLimit_of_comp {B : Type u₄} [Category.{v₄} B] {H : E ⥤ B} [PreservesLimit (F ⋙ G) H] :
PreservesLimit G H where
preserves {c}
hc := by
refine ⟨isLimitWhiskerEquiv F _ ?_⟩
let hc' := isLimitOfPreserves H ((isLimitWhiskerEquiv F _).symm hc)
exact IsLimit.ofIsoLimit hc' (Cones.ext (Iso.refl _) (by simp))