Articulation Node

Articulation Node

By removing node 1 from graph A, we obtain graph B, which is connected. 1 is thus not an articulation node. If we remove node 4 from graph A, the result is an un-connected graph C where p=2 (two subgraphs). Node 4 is thus the only articulation node of graph A. Removing any other node does not create two separate subgraphs.