English
For all f : α → β and g : M →+ N, the two ways of composing with mapDomain f and mapRange g commute.
Русский
Для любых f : α → β и g : M →+ N операции композиций с mapDomain f и mapRange g commutируют.
LaTeX
$$$$ (\mathrm{mapDomain.} \mathrm{addMonoidHom}\ f)\circ (\mathrm{mapRange.} \mathrm{addMonoidHom}\ g) = (\mathrm{mapRange.} \mathrm{addMonoidHom}\ g)\circ (\mathrm{mapDomain.} \mathrm{addMonoidHom}\ f). $$$$
Lean4
theorem addMonoidHom_comp_mapRange [AddCommMonoid N] (f : α → β) (g : M →+ N) :
(mapDomain.addMonoidHom f).comp (mapRange.addMonoidHom g) =
(mapRange.addMonoidHom g).comp (mapDomain.addMonoidHom f) :=
by
ext
simp