English
A kernel-preserving functor between preadditive categories preserves the binary product of any pair of objects.
Русский
Кернел-предохранющаяфункция между прeддвативными категориями сохраняет двоичное произведение пары объектов.
LaTeX
$$$\forall X,Y\,\ Pr oduct(X,Y)\implies PreservesLimit(\text{pair }X\ Y, F)$$$
Lean4
/-- A kernel-preserving functor between preadditive categories preserves any pair being a limit. -/
theorem preservesBinaryProduct_of_preservesKernels [∀ {X Y} (f : X ⟶ Y), PreservesLimit (parallelPair f 0) F]
{X Y : C} : PreservesLimit (pair X Y) F where
preserves {c}
hc :=
⟨IsLimit.ofIsoLimit (isLimitMapConeBinaryFanOfPreservesKernels F _ _ (IsLimit.ofIsoLimit hc (isoBinaryFanMk c)))
((Cones.functoriality _ F).mapIso (isoBinaryFanMk c).symm)⟩