English
If a is invertible in α, then sym(a)^{-1} = sym(a^{-1}) in the symmetrized algebra, matching the simplification symmetry.
Русский
Если a обратим в α, то в симметризованной алгебре выполняется sym(a)^{-1} = sym(a^{-1}).
LaTeX
$$$(\operatorname{sym} a)^{-1} = \operatorname{sym}(a^{-1})$$$
Lean4
@[simp]
theorem invOf_sym [Mul α] [AddMonoidWithOne α] [Invertible (2 : α)] (a : α) [Invertible a] : ⅟(sym a) = sym (⅟a) :=
rfl