“…A similar conjecture was proposed by Keller [10] removing the restriction that the centers of the cubes have to form a lattice, however this more stronger version was shown to be true in dimensions n ≤ 6 [25], false in dimensions n ≥ 8 [19,21] and it remains open in dimension n = 7. A lot of variants and problems related to cube tilings have been considered [14,15,16,29,30] as well as application to other areas such as combinatorics, graph Work partially supported by FAPESP grants 2012/10600-2 and 2013/25977-7 and by CNPq grants 312926/2013-8 and 158670/2015-9.…”