Figure 2. A toy example of extension and removal phases of GASOLINE algorithm in a pairwise alignment instance.

(a) The nodes of the two aligned subgraphs are highlighted in green. (b) In red are highlighted those adjacent nodes of current alignment which will be explored by the sampling algorithm during the next step of iterative phase. (c) At the end ot such iteration the alignment will be extended with a new node in each network. (d) Once the iterative phase completes, it gives as a result the aligned subgraphs highlighted in green. In (e) the removal step identifies the cyan nodes as those contributing less to the alignment score. (f) These will be replaced with those capable to increase the alignment score.