English
SpectrumRestricts is invariant under swapping the factors in a product: SpectrumRestricts (a·b) f ↔ SpectrumRestricts (b·a) f.
Русский
Свойство SpectrumRestricts сохраняется при перестановке множителей в произведении: SpectrumRestricts (a·b) f ↔ SpectrumRestricts (b·a) f.
LaTeX
$$$ SpectrumRestricts (a \\cdot b)\\ f \\iff SpectrumRestricts (b \\cdot a)\\ f $$$
Lean4
theorem mul_comm_iff {R S A : Type*} [Semifield R] [Field S] [Ring A] [Algebra R S] [Algebra R A] [Algebra S A]
{a b : A} {f : S → R} : SpectrumRestricts (a * b) f ↔ SpectrumRestricts (b * a) f :=
QuasispectrumRestricts.mul_comm_iff