English
There is a natural isomorphism from F.prod' G followed by fst to F, i.e. F.prod' G composed with fst B C is isomorphic to F.
Русский
Существует естественное изоморфизмe из F.prod' G, затем fst, в F.
LaTeX
$$$(F.prod' G) \\cdot \\mathrm{fst} \\cong F$$$
Lean4
/-- The Cartesian product of two natural isomorphisms. -/
@[simps]
def prod {F F' : A ⥤ B} {G G' : C ⥤ D} (e₁ : F ≅ F') (e₂ : G ≅ G') : F.prod G ≅ F'.prod G'
where
hom := NatTrans.prod e₁.hom e₂.hom
inv := NatTrans.prod e₁.inv e₂.inv