“…Fabila-Monroy et al, [15] reintroduced the concept of k-token graph of G as a model in which k indistinguishable tokens move on the vertices of a graph G along the edges of G. They began a systematic study of some combinatorial parameters of F k (G) such as connectivity, diameter, cliques, chromatic number, Hamiltonian paths and Cartesian product. This line of research has been continued by different authors, see, e.g., [5,12,13,16,19,23,24]. In particular Soto et al, [19] showed that a problem in coding theory is equivalent to the study of the packing number of the token graphs of the path graph.…”