The resulting matrix B has all the required properties for being a unit cell. Thus, each translation t ∈ 3 of an edge now corresponds to an offset o = B -1 t ∈ 3 with respect to the unit cell, so the lexicographically ordered set of edges (u, v, o) ∈ V × V × 3 is a representation of the initial graph that does not depend on its initial representation, but only on the candidate.