English
Reiterates that the product of two slash-invariant forms corresponds to the product of their value functions.
Русский
Повторение: произведение двух slash-инвариантных форм соответствует произведению их значений.
LaTeX
$$$\forall f,g,\ (f.mul g)(\tau) = f(\tau) \cdot g(\tau)\quad(\tau\in\mathbb{H}).$$$
Lean4
/-- Extensionality. See `ext` below for the version that will actually be used. -/
theorem ext' {χ χ' : MulChar R R'} (h : ∀ a, χ a = χ' a) : χ = χ' :=
by
cases χ
cases χ'
congr
exact MonoidHom.ext h