English
For any i, j with r: c.Rel i j, the kernel subobject of the differential from i to j equals the kernel subobject of the differential from i to the current target i.e., kernelSubobject (C.dFrom i) = kernelSubobject (C.d i j).
Русский
Для любых i, j с r: Rel i j верно, что ядро отображения из i в j совпадает с ядром отображения из i в i (то есть kernelSubobject (C.dFrom i) = kernelSubobject (C.d i j)).
LaTeX
$$$\\\\text{kernelSubobject}(C.dFrom i) = \\\\text{kernelSubobject}(C.d i j)$$$
Lean4
theorem kernel_eq_kernel [HasKernels V] {i j j' : ι} (r : c.Rel i j) (r' : c.Rel i j') :
kernelSubobject (C.d i j) = kernelSubobject (C.d i j') :=
by
rw [← d_comp_eqToHom C r r']
apply kernelSubobject_comp_mono