English
Let f: 𝕜 → 𝕜 be meromorphic at x and g: 𝕜 → E be meromorphic at x. Then f • g is meromorphic at x.
Русский
Пусть f: 𝕜 → 𝕜 и g: 𝕜 → E — мероморфны в x. Тогда f z · g z мероморфна в x.
LaTeX
$$$MeromorphicAt f x \\to MeromorphicAt g x \\to MeromorphicAt (fun z \\mapsto f z \\cdot g z) x$$$
Lean4
@[fun_prop]
theorem smul {f : 𝕜 → 𝕜} {g : 𝕜 → E} {x : 𝕜} (hf : MeromorphicAt f x) (hg : MeromorphicAt g x) :
MeromorphicAt (f • g) x := by
rcases hf with ⟨m, hf⟩
rcases hg with ⟨n, hg⟩
refine ⟨m + n, ?_⟩
convert hf.fun_smul hg using 2 with z
rw [Pi.smul_apply', smul_eq_mul]
module