English
If y ∈ connectedComponent x, then connectedComponent x = connectedComponent y.
Русский
Если y ∈ connectedComponent x, то connectedComponent x = connectedComponent y.
LaTeX
$$$y \in connectedComponent x \Rightarrow connectedComponent x = connectedComponent y$$$
Lean4
theorem connectedComponent_eq {x y : α} (h : y ∈ connectedComponent x) : connectedComponent x = connectedComponent y :=
eq_of_subset_of_subset (isConnected_connectedComponent.subset_connectedComponent h)
(isConnected_connectedComponent.subset_connectedComponent
(Set.mem_of_mem_of_subset mem_connectedComponent (isConnected_connectedComponent.subset_connectedComponent h)))