The electoral system for the Italian Senate - a case of deterministic chaos? (or how politicians can go wrong even when they do not want to)

The electoral system adopted for the allocation of seats in the Italian Senate utilizes a complex mechanism of awards at a regional level with the aim of strengthening, when necessary, the winning coalition and so improve overall government stability. By a systematic analysis of the award mechanism we demonstrate that in a significant number of cases, the effect of the mechanism is opposite to that desired, weakening the government by awarding more seats to the minority coalition, such that the minority coalition can become the majority and win the election. The award mechanism's output is actually strongly unpredictable, as it depends crucially on the precise details of the regional outcomes, thus closely resembling the behavior of chaotic dynamical systems.