concept

Articulation point

In graph theory, a node whose removal splits a once-connected graph into two disconnected pieces — also called a cut vertex. It is the sole bridge between two regions of a network: destroy it and the two sides can no longer reach each other. In a modular network, articulation points are the rare nodes that bridge clusters, which makes them strategic targets: you need not destroy much of the network, only the right bridging node, to amputate an entire region from the rest.