Edge versus vertex connectivity
Task number: 3961
Show that each vertex 2-connected graph is edge 2-connected.
(An edge 2-connected graph is such that after removing any edge remains connected.)
Solution
If the graph has a bridge and it is not \( K_2 \), then at least one of the ends of this bridge is adjacent to some other vertex and forms the articulation itself.
Variant
Find the smallest graph that is edge 2-connected but not vertex 2-connected.
Variant
For any pair of integers \( k \geq l \geq 2 \) construct a graph of edge connectivity \(k\) and vertex connectivity \(l\).