To develop the decision support system for courier dispatching, the problem is defined as finding the Hamiltonian circuit  with the minimum time, minimum distance and type of route travelled.
To determine the Hamiltonian circuit it self is a NP-complete problem and when shortest distance and minimum time is added with the Hamiltonian Cycle, it becomes a very hard optimization problem in the field of operations research.
Given a connected, undirected graph G with n nodes, a least cost Hamiltonian circuit H is a sub graph of a G that connects all of G's nodes and contains one cycle .
Today this is called finding a Hamiltonian circuit.
Other informative Gardner articles about Hamiltonian circuits include "Graph Theory: (Chapter 10 in [G71]), "'Knights of the Square Table" (Chapter 14 in [G77], and "'Uncrossed Knight's Tours (p.