English
As before, the extensional principle for restricted argument forms yields equality from equality at a distinguished input.
Русский
Как и ранее, принцип экстренсионности по особому входу даёт равенство по значимому аргументу.
LaTeX
$$f(1) = g(1) ⇒ f = g$$
Lean4
/-- If two continuous `R`-multilinear maps from `R` are equal on 1, then they are equal.
This is the multilinear version of `ContinuousLinearMap.ext_ring`. -/
@[ext]
theorem ext_ring [Finite ι] [TopologicalSpace R] ⦃f g : ContinuousMultilinearMap R (fun _ : ι => R) M₂⦄
(h : f (fun _ ↦ 1) = g (fun _ ↦ 1)) : f = g :=
toMultilinearMap_injective <| MultilinearMap.ext_ring h