English
For f: M → M' and g: N → N', the product map on sets is ContMDiffOn if f and g are ContMDiffOn on their respective domains.
Русский
Для функций f и g гладкость произведения сохраняется на множествах.
LaTeX
$$$\\displaystyle \\operatorname{ContMDiffOn} \\; I \\; (I'.prod J') \\; n \\; (\\mathrm{Prod.map} \\; f \\; g) \\; (s \\times^\\! r) \\; p$$$
Lean4
/-- Curried `C^n` functions are `C^n` in the first coordinate. -/
theorem curry_left {f : M → M' → N} {s : Set (M × M')} (fa : ContMDiffOn (I.prod I') J n (uncurry f) s) {y : M'} :
ContMDiffOn I J n (fun x ↦ f x y) {x | (x, y) ∈ s} := fun x m ↦ (fa (x, y) m).along_fst