192 N.F. McPhee et al.
4.1 Working Backwards
A natural place to start our analysis is at the end of the run, when the GP system
created one or more individuals that solved the problem. So we used Neo4j to find
all the ancestors of any “winning” individual, i.e., an individual with a total error of
zero represented than others. As we’ve already mentioned, individual 86:261 has 45
successful offspring, and both individuals 82:447 and 83:047 have five offspring
in the graph, i.e., five offspring that were ancestors of a winning individual in
generation 87. Each of these is marked in Fig. 1 with a shaded diamond.
Gen 79
Gen 80
Gen 81
Gen 82
Gen 83
Gen 84
Gen 85
Gen 86
Gen 87
80:220
82:447
83:124 83:619 83:047
84:319
85:086
86:261
87:941 42 Other Winners 87:719 87:947
Fig. 1 Ancestry of the 45 “winners” from a successful run of replace-space-with-newline using
lexicase.Diamond-shapednodes had an unusually large number of offspring (over 100 each).
Shaded nodeshad at least five offspring that were ancestors of winners