Comparator and Ranking

Hi,

I’m currently using the jMetal 5.0 library and I realized that even if I have implemented my own Comparator (in order to maximize objectives instead of minimizing for instance), the NSGAII algorithm will call the SolutionListUtils.getNondominatedSolutions(solutionList) mehtod which uses a DominanceRanking that obviously does not involve my own Comparator.

I’m not sure that it is a lack in the features of the library of I’m incorrectly using it… Can someone help me ?

I’m not sure that this kind of post has to be here, so please tell me if it has not

[matthieu-vergne]

If at the end, it reduces to a single evaluation, the multi-objective part maybe not particularly interesting for you. A basic idea otherwise is to consider them equally during the run, so just donc care about this priority, and at the end consider it to retrieve the best individual from the population returned. I used it in that way, personally, although I don’t know whether or not it is recommended. {'^_^}

[ajnebro]

The constraint handling mechanism used in jMetal is the one used in NSGA-II (http://sci2s.ugr.es/sites/default/files/files/Teaching/OtherPostGraduateCourses/MasterEstructuras/bibliografia/Deb_NSGAII.pdf).

The overall constraint violation assumes that all the constraints are defined in the form C > 0, so the larger the value of C, the larger the degree of constraint violation. You can take as examples problems SRN, CONSTR and TNK in Table V of Deb’s paper and the corresponding implementations in jMetal (problems Srinivas, ConstrEx and Tanaka in https://github.com/jMetal/jMetal/tree/master/jmetal-problem/src/main/java/org/uma/jmetal/problem/multiobjective).