We show that optimal partisan redistricting with geographical constraints is a computationally intractable (NP-complete) problem. In particular, even when voter's preferences are deterministic, a solution is generally not obtained by concentrating opponent's supporters in "unwinnable" districts...

We show that even when voters’ preferences are deterministic and known optimal partisan redistricting is not generally obtained by concentrating opponent’s supporters in “unwinnable” districts (“packing”) and spreading one’s own supporters evenly among the other districts in order...