English
WithZero α inherits the right distributive law from α: a·(b+c) = a·b + a·c for all a,b,c in WithZero α.
Русский
WithZero α наследует правовую распределимость от α: для любых a,b,c выполняется a·(b+c) = a·b + a·c в WithZero α.
LaTeX
$$$\\forall a,b,c \\in \\mathrm{WithZero}\\,\\alpha,\\ a \\cdot (b + c) = a \\cdot b + a \\cdot c$$$
Lean4
instance instRightDistribClass [Mul α] [Add α] [RightDistribClass α] : RightDistribClass (WithZero α) where
right_distrib a b
c := by
cases c; · simp
cases a <;> cases b <;> try rfl
exact congr_arg some (right_distrib _ _ _)