Chapter 4.15
Sequencing Problem

1. Hamiltonian Path: Given a undirected graph G, there exists a hamiltonian path, if and only if there exists a path, in which every vertex is visited exactly once.
2. Hamiltonian Cycle : Given a undirected graph G, there exists a hamiltonian cycle, if and only if there exists a cycle, in which every vertex is visited exactly once. Note that, one node can be allowed to close the cycle, so that node would visit twice.
3. Directed Hamiltonian Cycle: Given a directed graph G, there exists a hamiltonian cycle, if and only if there exists a cycle, in which every vertex is visited exactly once.
4. Travelling Salesman Problem
5. Longest Path: Given a digraph G = (V, E), find the longest path in the graph.