English
If x ∈ F and y ∈ F with y ∈ connectedComponentIn F x, then connectedComponentIn F x = connectedComponentIn F y.
Русский
Если x ∈ F и y ∈ F и y ∈ connectedComponentIn F x, то connectedComponentIn F x = connectedComponentIn F y.
LaTeX
$$$y \in connectedComponentIn F x \Rightarrow connectedComponentIn F x = connectedComponentIn F y$$$
Lean4
theorem connectedComponentIn {x : α} {F : Set α} (h : IsPreconnected F) (hx : x ∈ F) : connectedComponentIn F x = F :=
(connectedComponentIn_subset F x).antisymm (h.subset_connectedComponentIn hx subset_rfl)