English
In a setup with actions and commutativity, the left-smul by g on a is equivalent to commuting after reversing the order: g • a and b commute iff a and b commute after smul_right by g.
Русский
При некоторых условиях эквивалентно: g • a и b коммутируют тогда и только тогда, когда a и b коммутируют после правого умножения на g.
LaTeX
$$$\\\\forall g \\\\in G, \\\\forall a \\\\in α, \\\\forall b \\\\in α, \\\\ Commute (g \\\\cdot a) b \\\\iff \\\\ Commute a b.$$$
Lean4
@[simp]
theorem smul_right_iff : Commute a (g • b) ↔ Commute a b :=
⟨fun h ↦ inv_smul_smul g b ▸ h.smul_right g⁻¹, fun h ↦ h.smul_right g⟩