19 research outputs found
Approximate Maximin Shares for Groups of Agents
We investigate the problem of fairly allocating indivisible goods among
interested agents using the concept of maximin share. Procaccia and Wang showed
that while an allocation that gives every agent at least her maximin share does
not necessarily exist, one that gives every agent at least of her share
always does. In this paper, we consider the more general setting where we
allocate the goods to groups of agents. The agents in each group share the same
set of goods even though they may have conflicting preferences. For two groups,
we characterize the cardinality of the groups for which a constant factor
approximation of the maximin share is possible regardless of the number of
goods. We also show settings where an approximation is possible or impossible
when there are several groups.Comment: To appear in the 10th International Symposium on Algorithmic Game
Theory (SAGT), 201
How to Cut a Cake Fairly: A Generalization to Groups
A fundamental result in cake cutting states that for any number of players
with arbitrary preferences over a cake, there exists a division of the cake
such that every player receives a single contiguous piece and no player is left
envious. We generalize this result by showing that it is possible to partition
the players into groups of any desired sizes and divide the cake among the
groups, so that each group receives a single contiguous piece and no player
finds the piece of another group better than that of the player's own group
Computing an Approximately Optimal Agreeable Set of Items
We study the problem of finding a small subset of items that is
\emph{agreeable} to all agents, meaning that all agents value the subset at
least as much as its complement. Previous work has shown worst-case bounds,
over all instances with a given number of agents and items, on the number of
items that may need to be included in such a subset. Our goal in this paper is
to efficiently compute an agreeable subset whose size approximates the size of
the smallest agreeable subset for a given instance. We consider three
well-known models for representing the preferences of the agents: ordinal
preferences on single items, the value oracle model, and additive utilities. In
each of these models, we establish virtually tight bounds on the approximation
ratio that can be obtained by algorithms running in polynomial time.Comment: A preliminary version appeared in Proceedings of the 26th
International Joint Conference on Artificial Intelligence (IJCAI), 201
Cutting a Cake Fairly for Groups Revisited
Cake cutting is a classic fair division problem, with the cake serving as a
metaphor for a heterogeneous divisible resource. Recently, it was shown that
for any number of players with arbitrary preferences over a cake, it is
possible to partition the players into groups of any desired size and divide
the cake among the groups so that each group receives a single contiguous piece
and every player is envy-free. For two groups, we characterize the group sizes
for which such an assignment can be computed by a finite algorithm, showing
that the task is possible exactly when one of the groups is a singleton. We
also establish an analogous existence result for chore division, and show that
the result does not hold for a mixed cake
Strategyproof Mechanisms For Group-Fair Facility Location Problems
We study the facility location problems where agents are located on a real
line and divided into groups based on criteria such as ethnicity or age. Our
aim is to design mechanisms to locate a facility to approximately minimize the
costs of groups of agents to the facility fairly while eliciting the agents'
locations truthfully. We first explore various well-motivated group fairness
cost objectives for the problems and show that many natural objectives have an
unbounded approximation ratio. We then consider minimizing the maximum total
group cost and minimizing the average group cost objectives. For these
objectives, we show that existing classical mechanisms (e.g., median) and new
group-based mechanisms provide bounded approximation ratios, where the
group-based mechanisms can achieve better ratios. We also provide lower bounds
for both objectives. To measure fairness between groups and within each group,
we study a new notion of intergroup and intragroup fairness (IIF) . We consider
two IIF objectives and provide mechanisms with tight approximation ratios
Maximin Fairness with Mixed Divisible and Indivisible Goods
We study fair resource allocation when the resources contain a mixture of
divisible and indivisible goods, focusing on the well-studied fairness notion
of maximin share fairness (MMS). With only indivisible goods, a full MMS
allocation may not exist, but a constant multiplicative approximate allocation
always does. We analyze how the MMS approximation guarantee would be affected
when the resources to be allocated also contain divisible goods. In particular,
we show that the worst-case MMS approximation guarantee with mixed goods is no
worse than that with only indivisible goods. However, there exist problem
instances to which adding some divisible resources would strictly decrease the
MMS approximation ratio of the instance. On the algorithmic front, we propose a
constructive algorithm that will always produce an -MMS allocation for
any number of agents, where takes values between and and is
a monotone increasing function determined by how agents value the divisible
goods relative to their MMS values.Comment: Appears in the 35th AAAI Conference on Artificial Intelligence
(AAAI), 202