Rank each member by the number of members that dominate it


  • Alias: None

  • Arguments: None


The fitness_type: domination_count has been specifically designed to avoid problems with aggregating and scaling objective function values and transforming them into a single objective.

Instead, the domination_count fitness assessor works by ordering population members by the negative of the number of designs that dominate them. The values are negated in keeping with the convention that higher fitness is better.

The layer_rank fitness assessor works by assigning all non-dominated designs a layer of 0, then from what remains, assigning all the non-dominated a layer of 1, and so on until all designs have been assigned a layer. Again, the values are negated for the higher-is-better fitness convention.

Use of the below_limit selector with the domination_count fitness assessor has the effect of keeping all designs that are dominated by fewer then a limiting number of other designs subject to the shrinkage limit.

Using it with the layer_rank fitness assessor has the effect of keeping all those designs whose layer is below a certain threshold again subject to the shrinkage limit.