perlquestion Limbic~Region All, <br /> I would like to find a way to generate the [wp://powerset] such that all subsets below the current set can be skipped if a condition is met. I think a concrete example might better explain. Assume our set contains 'A' .. 'D'; <CODE> A, B, C, D AB, AC, AD, BC, BD, CD ABC, ABD, ACD, BCD ABCD </CODE> I omitted the empty set as it has no practical purposes for my problem. The following re-ordering is an example of the optimization I am hoping to use: <CODE> ABCD ABC AB A B AC C BC ABD AD D BD ACD CD BCD </CODE> So if the condition for 'ABCD' was true, I would skip the entire powerset. If 'ABC' was true I would skip to 'ABD'. If 'ABD' was false but 'AD' was true I would skip to 'BD'. <p> This exact ordering isn't necessary and I am not sure if it helped explain my desire at all. Ultimately the goal is to generate the powerset for a list of sets but avoid duplication where possible. Using another example: </p> <CODE> Set1: A,B,C,D Set2: A,B,C,E set3: A,B,C,F,G </CODE> They share sets ABC, AB, AC, BC, A, B, and C so why generate them three times? I have used a similar [id://434517|technique] in the past with success but I can't seem to wrap my head around how to do it here. Your thoughts and insights are appreciated. <p> <b>Update:</b> It was suggested in a /msg that I be more specific about the rules and not assume the examples are sufficient. <ul> <li>If a set has previously been seen, all subsets of that set can be skipped</li> <li>The powerset should be generated in a manner that maximizes the potential for optimization. In other words, A,B,C should be generated before A,C</li> <li>No more sets should be generated than would otherwise be done using a [id://576122|straight forward iterative approach]. In other words, A, B, C should produce only 7 candidates (or less if optimization possible)</li> </ul> </p> <div class="pmsig"><div class="pmsig-180961"> <p> Cheers - [Limbic~Region|L~R] </p> </div></div>