Finally, the algorithm can be made faster by changing the mode of comparison of the candidates. In Systre, the topological genome was defined as the smallest key extracted from a candidate. However, we observe that, arrived at step (h) of the algorithm in Figure , both the embedding of the graph as well as the ordering of its vertices only depend on the candidate. Hence, we can define at that point a pseudo-key consisting in the sorted list of triplets ) ∈ V ×V × 3 if there is an edge between the vertex defined by its number s and the representative of vertex number d which is translated from the latter by t. This pseudo-key only depends on the intermediate representation of the graph obtained in step (h), which means it is exclusively determined by the candidate, so we can define the genome as the key extracted from the candidate with the smallest pseudo-key.