Joints

如果有两个或者更多的边共享了一个节点的起点（不仅仅指一个方向）它们会在路径的某一处分叉；同样，如果一个或者多个边共享了一个节点的终点，那么它们会在某个地方汇合。

  1. [ Potsdam ], [ Mannheim ]
  2.    --> { end: back,0; }
  3.  [ Weimar ]
  4.    --> { start: front,0; } [ Finsterwalde ], [ Aachen ]

Joints - 图1

  1. +----------+           +--------+          +--------------+
  2. | Mannheim | ------+-> | Weimar | -+-----> | Finsterwalde |
  3. +----------+       |   +--------+  |       +--------------+
  4.                    |               |
  5.                    |               |
  6.                    |               |
  7. +----------+       |               |       +--------------+
  8. | Potsdam  | ------+               +-----> |    Aachen    |
  9. +----------+                               +--------------+

这个机制可以和边的标签一起使用：

  1. [ Jena ] 
  2.  -- train --> { start: front, 0; } 
  3.   [ Augsburg ], [ Ulm ]
  4. [ Jena ] -- car --> { start: front, 0; } [ Plauen ]

Joints - 图2

  1. +------+           train    +----------+
  2. | Jena | ------+----------> |   Ulm    |
  3. +------+       |            +----------+
  4.                |   train    +----------+
  5.                +----------> | Augsburg |
  6.                |            +----------+
  7.                |    car     +----------+
  8.                +----------> |  Plauen  |
  9.                             +----------+