핵심 개념
Every 3-connected graph can be uniquely decomposed into parts that are either quasi 4-connected, wheels, or thickened K3,m's.
초록
The paper introduces a new structural basis for the theory of 3-connected graphs, providing a unique decomposition of every such graph. The key aspects are:
- Relaxing the notion of 4-connectivity to quasi 4-connectivity, where every 3-separation has a side of size at most 4.
- Introducing the new concept of a tri-separation, which uses both vertices and edges to separate the graph.
- Showing that every 3-connected graph can be uniquely decomposed into parts that are either quasi 4-connected, wheels, or thickened K3,m's, by cutting along the totally-nested nontrivial tri-separations.
The authors prove several structural results about tri-separations, including a classification of 3-connected graphs without any totally-nested nontrivial tri-separations. They also provide applications of their decomposition, such as a new characterization of Cayley graphs and an automatic proof of Tutte's wheel theorem.