4 research outputs found
Proportionally Representative Participatory Budgeting: Axioms and Algorithms
Participatory budgeting is one of the exciting developments in deliberative
grassroots democracy. We concentrate on approval elections and propose
proportional representation axioms in participatory budgeting, by generalizing
relevant axioms for approval-based multi-winner elections. We observe a rich
landscape with respect to the computational complexity of identifying
proportional budgets and computing such, and present budgeting methods that
satisfy these axioms by identifying budgets that are representative to the
demands of vast segments of the voters
Participatory Budgeting: Models and Approaches
Participatory budgeting is a democratic approach to deciding the funding of
public projects, which has been adopted in many cities across the world. We
present a survey of research on participatory budgeting emerging from the
computational social choice literature, which draws ideas from computer science
and microeconomic theory. We present a mathematical model for participatory
budgeting, which charts existing models across different axes including whether
the projects are treated as "divisible" or "indivisible" and whether there are
funding limits on individual projects. We then survey various approaches and
methods from the literature, giving special emphasis on issues of preference
elicitation, welfare objectives, fairness axioms, and voter incentives.
Finally, we discuss several directions in which research on participatory
budgeting can be extended in the future
Participatory Budgeting with Cumulative Votes
In participatory budgeting we are given a set of projects---each with a cost,
an available budget, and a set of voters who in some form express their
preferences over the projects. The goal is to select---based on voter
preferences---a subset of projects whose total cost does not exceed the budget.
We propose several aggregation methods based on the idea of cumulative votes,
e.g., for the setting when each voter is given one coin and she specifies how
this coin should be split among the projects. We compare our aggregation
methods based on (1) axiomatic properties, and (2) computer simulations. We
identify one method, Minimal Transfers over Costs, that demonstrates
particularly desirable behavior. In particular, it significantly improves on
existing methods, satisfies a strong notion of proportionality, and, thus, is
promising to be used in practice
Knapsack Voting for Participatory Budgeting
We address the question of aggregating the preferences of voters in the
context of participatory budgeting. We scrutinize the voting method currently
used in practice, underline its drawbacks, and introduce a novel scheme
tailored to this setting, which we call "Knapsack Voting". We study its
strategic properties - we show that it is strategy-proof under a natural model
of utility (a dis-utility given by the distance between the outcome
and the true preference of the voter), and "partially" strategy-proof under
general additive utilities. We extend Knapsack Voting to more general settings
with revenues, deficits or surpluses, and prove a similar strategy-proofness
result. To further demonstrate the applicability of our scheme, we discuss its
implementation on the digital voting platform that we have deployed in
partnership with the local government bodies in many cities across the nation.
From voting data thus collected, we present empirical evidence that Knapsack
Voting works well in practice