|Salle C 108 (1er étage), Université Paris-Dauphine|
"Unanimous Implementation: A Case for Approval Mechanisms"
A committee of experts must decide on the value of a numerical variable (the interest rate for instance). Experts have different views on the value that should be adopted. Usual methods face a number of shortcomings, such as allowing for manipulation or failing to give incentives for coordination. To avoid these problems, we design the class of Approval mechanisms which allow the experts to report ranges of values. By focusing on the single-peaked domain, we prove that each of these mechanisms is characterized by a unique moderate equilibrium outcome. More importantly, they minimize the susceptibility of the collective decision to manipulations by agents with extreme opinions. Finally, we show that Approval mechanisms lead to policy outcomes that are approved by everyone, fostering unanimous agreements.