English
If two continuous multilinear maps f,g into a product have equal first-projections and equal second-projections, then f=g.
Русский
Если две непрерывные мультилинейные карты f,g в произведение имеют равные проекции fst и snd, тогда они равны.
LaTeX
$$$\text{prod_ext}\; (h_1,h_2) : (\forall f,g, (\text{fst}.\circ f)=(\text{fst}.\circ g) \land (\text{snd}.\circ f)=(\text{snd}.\circ g) \Rightarrow f=g$$$
Lean4
theorem eq_prod_iff {f : ContinuousMultilinearMap R M₁ (M₂ × M₃)} {g : ContinuousMultilinearMap R M₁ M₂}
{h : ContinuousMultilinearMap R M₁ M₃} :
f = g.prod h ↔
(ContinuousLinearMap.fst _ _ _).compContinuousMultilinearMap f = g ∧
(ContinuousLinearMap.snd _ _ _).compContinuousMultilinearMap f = h :=
prod_ext_iff