PhD thesis

"Collective decision-making under the influence of bribers and temporal constraints"

July 2016

In my PhD thesis I study the connection between corruption and structural characteristics of parliaments: number of seats, the number of partiesrepresented, and decision rules adopted. Following analytical and computational approaches, and running simulations, I show that the averagenumber of deputies needed to be bribed by a briber in order to achieve a desired for him decision decreases as the number of parties increases, sobribery is encouraged by a growing number of parties.

I also investigate two ways in which time may affect decision-making. First, I suggest a game-theoretical model of an iterative voting procedure inwhich delay to reach a decision is costly. For two voters and two options, with a fixed voting order, I prove that in the unique subgame perfectequilibrium of the game the voter who votes first obtains his most preferred option at the beginning of the procedure. If the fixed order is reversed onceat some stage, I identify the condition under which the voter initially voting the second obtains his most preferred option, also at the beginning.

Second, I propose another iterative voting procedure, allowing voters to change their votes, but now with a deadline: a stage such that, if no decisionhas been taken by then, the worst outcome results. I show that (i) if there is enough time for all the voters to change their vote, a decision will betaken, and (ii) if there is an alternative preferred by a majority of the voters, this alternative will be finally chosen. I add an experimental studyindicating that even with less time necessary for every voter to change his vote, the voters will agree with a decision anyway.