Articulation Points - Edge Cases

$1.$ Single vertex: $n=1$.

No articulation points (cannot remove the only vertex and have a meaningful result). Output: $[]$.

$2.$ Two vertices, one edge: $n=2$, edge $0-1$.

No articulation points by standard definition. Output: $[]$.

$3.$ Star graph: $n=4$, edges $[[0,1],[0,2],[0,3]]$.

Center $0$ is an articulation point if $n \geq 3$. Output: $[0]$.

$4.$ Cycle: no articulation points.

Every vertex has two neighbors. Output: $[]$.