Axioms and Algorithms for Participatory Budgeting

Participatory budgeting is a recent, exciting development in deliberative grassroots democracy in which, e.g., residents of a city specify their preferences on how to construct their city budget, and an algorithm is then applied to aggregate their preferences and decide upon the budget. Even though it is gaining increasing popularity and is used to decide upon many millions of dollars every year, the foundations of participatory budgeting are not yet well understood. I will discuss some recent developments, specifically novel, efficient aggregation algorithms satisfying certain axiomatic properties desired in participatory budgeting scenarios.