English
The product map is ContMDiff; i.e., the map (u,v) ↦ u v from G × G to G is C^n.
Русский
Карта умножения на произведение является ContMDiff, т.е. (u,v) ↦ uv из G×G в G — C^n.
LaTeX
$$$$ \ContMDiff (I \prod I) I n \bigl(\lambda p : G \times G, p_1 p_2\bigr) $$$$
Lean4
/-- If the multiplication is `C^n`, then it is continuous. This is not an instance for technical
reasons, see note [Design choices about smooth algebraic structures]. -/
@[to_additive /-- If the addition is `C^n`, then it is continuous. This is not an instance for
technical reasons, see note [Design choices about smooth algebraic structures]. -/
]
theorem continuousMul_of_contMDiffMul [ContMDiffMul I n G] : ContinuousMul G :=
⟨(contMDiff_mul I n).continuous⟩