Algorithm 3: Environmental Selection

Input: $Q$ , $Z$ , $z$

Output: $P$

1: $F\leftarrow Nondominatedsort(Q)$

2: Last front to be included: $F_l$

3: $CP\leftarrow {\displaystyle {\cup }_{i=1}^l{F}_i}$

4: if $\left|CP\right|=N$ then

5: return $P\leftarrow CP$

6: else

7: $C{P}^{\prime }\leftarrow {\displaystyle {\cup }_{i=1}^{l-1}{F}_i}$

8: Points to be chosen from $F_l$ : $K\leftarrow N-\left|C{P}^{\prime }\right|$

9: $C{P}^{″}\leftarrow F_l$

10: Normalize objectives: $C{P}^{‴}\leftarrow \frac{F_l-\min (F_l)}{\max (F_l)-\min (F_l)}$

11: Associate each member s of $C{P}^{‴}$ a reference point: $AR\leftarrow Associate(C{P}^{‴},Z)$

12: closest reference point: $\delta \leftarrow sort(AR)$

13: return $P\leftarrow C{P}^{\prime }\cup {\delta }_K$

14: end if