maxpalmer

Suppose you're defining as Party B, and you draw 8 majority-B districts (2:3) and 2 majority-A districts. Then, when Party A is combining, they would pair each of the majority-A districts with a majority-B district with a smaller margin, resulting in 2 A districts and 3 B districts. This is an improvement compared to if B drew 5 districts unilaterally, where it could draw 4 majority-B districts.

You're right that this method doesn't protect incumbents. However, protecting incumbency and avoiding open-seat elections isn't necessarily a bad thing, and could increase electoral competition in some places. Some states don't allow incumbency to be taken into account when redistricting already.

Yes, that would work. The paper has a note about excluding districts like this:

> "Valid districts are contiguous and have equal population. Strict constraints on compactness, geographic splits, or other restrictions are not necessary, but such limitations could be included. However, valid districts may not include “donuts,” where one district entirely encircles another."

Potentially in some form, but we haven't investigated it. The utility functions for each party would be very different. Instead of trying to maximize the seats that they win, parties would also need to think about the coalitions that could form if no party won a majority of the seats.