*6.2. Figure of Merits*

The performance of approaches is assessed regarding the following figures of merit. The first three are the most popular and represent the strongest quality indicators [20]. The fourth has been taken from [47] and sometimes can be useful to explain the results concerning the first two. The fifth was inspired by [48] in order to measure the connectivity quality. Besides, a sixth indicator is proposed here in order to have a better qualitative analysis of the connectivity aspects. Moreover, the connected components of the topology along the exploration are also plotted. The indicators are defined as follows:

