Political districting: Traps, criteria, algorithms and tradeoffs

In modern democracies, political districting has often been flawed by manipulation aiming to favour some specific party. To prevent such gerrymandering practices, operations researchers have developed many different automatic and neutral districting procedures, based on single- or multiple-objective optimization. After pinpointing some of the traps hidden in the districting process, we review some selected models and their solution algorithms, focusing on some critical issues such as the choice of criteria and their indicators, as well as the analysis of trade-offs between different criteria.