English
For AddCommGroup α, LinearOrder α, IsOrderedAddMonoid α, (-a).untop₀ = -a.untop₀ for any a in WithTop α.
Русский
Для AddCommGroup α, LinearOrder α, IsOrderedAddMonoid α: (-a).untop₀ = -a.untop₀.
LaTeX
$$$[AddCommGroup \alpha] [LinearOrder \alpha] [IsOrderedAddMonoid \alpha]\; (-a).untop_0 = -a.untop_0$$$
Lean4
@[simp]
theorem untop₀_neg [AddCommGroup α] [LinearOrder α] [IsOrderedAddMonoid α] (a : WithTop α) : (-a).untop₀ = -a.untop₀ :=
by
cases a with
| top => simp
| coe a =>
rw [← LinearOrderedAddCommGroup.coe_neg, untop₀_coe]
simp