Almerich-Chulia, Ana; Cabrera Martinez, Abel; Hernandez Mira, Frank Angel; Martín Concepcion, Pedro Efrén(MDPI AG, 2021-07-16)
[EN] Let G be a graph with no isolated vertex and let N (v) be the open neighbourhood of v is an element of V (G). Let f : V (G) -> {0, 1, 2} be a function and V-i = {v is an element of V (G) : f (v) = i} for every i is ...