Figure 4.

Illustration of the two possible routes a cycles can close. Top route: The cycles closes with the addition of triangles. The cycles representative will be the original cycles 〈abcdef〉, irrespectively of the life time of the sub cycles that are partially closed. Bottom route: The original cycle is split into smaller cycles that are eventually closed by the mechanism illustrated in the top route. The two cycles that will be represented in the original cycle 〈abcdef〉 and the subcycle 〈abcd〉, as the cycle 〈adef〉 can be obtained as a linear combination of the first two.