4,260 research outputs found
Mechanism Design without Money via Stable Matching
Mechanism design without money has a rich history in social choice
literature. Due to the strong impossibility theorem by Gibbard and
Satterthwaite, exploring domains in which there exist dominant strategy
mechanisms is one of the central questions in the field. We propose a general
framework, called the generalized packing problem (\gpp), to study the
mechanism design questions without payment. The \gpp\ possesses a rich
structure and comprises a number of well-studied models as special cases,
including, e.g., matroid, matching, knapsack, independent set, and the
generalized assignment problem.
We adopt the agenda of approximate mechanism design where the objective is to
design a truthful (or strategyproof) mechanism without money that can be
implemented in polynomial time and yields a good approximation to the socially
optimal solution. We study several special cases of \gpp, and give constant
approximation mechanisms for matroid, matching, knapsack, and the generalized
assignment problem. Our result for generalized assignment problem solves an
open problem proposed in \cite{DG10}.
Our main technical contribution is in exploitation of the approaches from
stable matching, which is a fundamental solution concept in the context of
matching marketplaces, in application to mechanism design. Stable matching,
while conceptually simple, provides a set of powerful tools to manage and
analyze self-interested behaviors of participating agents. Our mechanism uses a
stable matching algorithm as a critical component and adopts other approaches
like random sampling and online mechanisms. Our work also enriches the stable
matching theory with a new knapsack constrained matching model
Knapsack based Optimal Policies for Budget-Limited Multi-Armed Bandits
In budget-limited multi-armed bandit (MAB) problems, the learner's actions
are costly and constrained by a fixed budget. Consequently, an optimal
exploitation policy may not be to pull the optimal arm repeatedly, as is the
case in other variants of MAB, but rather to pull the sequence of different
arms that maximises the agent's total reward within the budget. This difference
from existing MABs means that new approaches to maximising the total reward are
required. Given this, we develop two pulling policies, namely: (i) KUBE; and
(ii) fractional KUBE. Whereas the former provides better performance up to 40%
in our experimental settings, the latter is computationally less expensive. We
also prove logarithmic upper bounds for the regret of both policies, and show
that these bounds are asymptotically optimal (i.e. they only differ from the
best possible regret by a constant factor)
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