English
The map (diagramCompIso F P X).hom is compatible with the universal arrows ι of the multicospan diagram, i.e., the expected compatibility condition holds.
Русский
Гом-компонента diagramCompIso F P X совместима с стрелами ι многоцепной диаграммы.
LaTeX
$$$(J.diagramCompIso F P X).hom \circ ι = F.map(ι)$$$
Lean4
@[reassoc (attr := simp)]
theorem whiskerRight_toPlus_comp_plusCompIso_hom : whiskerRight (J.toPlus _) _ ≫ (J.plusCompIso F P).hom = J.toPlus _ :=
by
ext
dsimp [toPlus]
simp only [ι_plusCompIso_hom, Functor.map_comp, Category.assoc]
simp only [← Category.assoc]
congr 1
dsimp only [diagram] -- Need to unfold `diagram` before `ext` applies.
ext a
rw [Category.assoc, diagramCompIso_hom_ι, ← F.map_comp]
simp only [unop_op, limit.lift_π, Multifork.ofι_π_app, Functor.comp_obj, Functor.comp_map]