相关文献：
Rego, C. (1998). "A Subpath Ejection Method for the Vehicle Routing Problem." Management Science 44(10): 1447-1459.
Glover, F. (1996). "Ejection chains, reference structures and alternating path methods for traveling salesman problems." Discrete Applied Mathematics 65(1-3): 223-253.
核心内容：集成ejection chain processes的邻域搜索算法求解组合优化问题。
分为两类：node(or block) ejection procedure 和 subpath ejection
The stem-and-cycle reference structure 是包含一个简单圈和与之相接的一条路的生成子图，这条路叫茎(stem)，茎与圈的连接点是根结点r，茎的端点为t。
交错路(alternating path)是一条简单路径，满足任意相邻的两条边，一条在匹配内，一条不在匹配内。
Let M be a matching in a graph G. An M-alternating path or cycle in G is a path or cycle whose edges are alternately in M and EM. An M-alternating path might or might not start or end with edges of M.