About the use of NSGA-II and NSGA-III and how the output variables are computed

[RafaHPSUnicamp]

Hi, I have a problem that have 8 output variables. My problem is required to use the maximum of the profit and use the minimum of the area (output variables). 4 areas have better productivity and have 0 cost. The other 4 are a lower productivity, and have a value to use, different from the first 4. Also, all areas have a limit to use. I played my code in NSGA-II and NSGA-III and the better areas was not using at 100%, but the other areas have at least 60% to use, since the are worst, because have a lower producitity and have a cost.

A lower productivity in this case means more use in areas to maximize profit. A higher productivity means less use of areas to maximize profit. Again, the objetive is maximize profit and minimize the sum of output variables (areas).

So, why NSGA-II and NSGA-III is not using 100% of the areas which have no cost and have a better productivity, and using some of the areas that have a less productivity and have a cost to use? Is related to how that algorithms works?

Another important detail: the problem does not have a restriction related to minimum ammount of each area to use, but have a restriction related to maximum use of the area.