# Chinese postman problem

### From Glossary

A mailman starts from the post office, delivers the mail on his route, covering each street at least once, then returns to the post office. The problem is to find a traversal such that the total distance travelled is minimized. (Some streets are one-way, and the postman is driving.) Abstractly, the problem is to find a least-cost cycle in a graph that uses each edge and arc (forward direction only) at least once. This differs from the Traveling Salesman Problem in that the postman can traverse an edge more than once. A related problem is to determine whether the postman can cover his route within a prescribed distance (while starting and ending at his post office). If so, the cycle is produced. This is computationally equivalent to the minimization problem (in a complexity sense), and is sometimes taken as the problem definition.