Vertex separator

A **vertex separator** (or simply "separator") is a concept in graph theory. It is a set of vertices whose removal disconnects the graph, meaning that it separates the graph into two or more disjoint subgraphs. More formally, given a connected graph \( G \) and a subset of vertices \( S \) in \( G \), \( S \) is called a vertex separator if removing \( S \) from \( G \) results in a graph that is not connected.