English
If f is continuous at x and x has a MapClusterPt x F u, then MapClusterPt (f x) F (f ∘ u).
Русский
Если f непрерывна в x и x имеет MapClusterPt x F u, то MapClusterPt (f x) F (f ∘ u).
LaTeX
$$$\\text{ContinuousAt}(f,x) \\Rightarrow \\mathrm{MapClusterPt}(x,F,u) \\Rightarrow \\mathrm{MapClusterPt}(f(x),F,f\\circ u)$$$
Lean4
theorem continuousAt_comp [TopologicalSpace Y] {f : X → Y} (hf : ContinuousAt f x) (hu : MapClusterPt x F u) :
MapClusterPt (f x) F (f ∘ u) :=
hu.tendsto_comp hf