16 research outputs found
Approaching Utopia: Strong Truthfulness and Externality-Resistant Mechanisms
We introduce and study strongly truthful mechanisms and their applications.
We use strongly truthful mechanisms as a tool for implementation in undominated
strategies for several problems,including the design of externality resistant
auctions and a variant of multi-dimensional scheduling
An Improved Randomized Truthful Mechanism for Scheduling Unrelated Machines
We study the scheduling problem on unrelated machines in the mechanism design
setting. This problem was proposed and studied in the seminal paper (Nisan and
Ronen 1999), where they gave a 1.75-approximation randomized truthful mechanism
for the case of two machines. We improve this result by a 1.6737-approximation
randomized truthful mechanism. We also generalize our result to a
-approximation mechanism for task scheduling with machines, which
improve the previous best upper bound of $0.875m(Mu'alem and Schapira 2007)
A characterization of 2-player mechanisms for scheduling
We study the mechanism design problem of scheduling unrelated machines and we
completely characterize the decisive truthful mechanisms for two players when
the domain contains both positive and negative values. We show that the class
of truthful mechanisms is very limited: A decisive truthful mechanism
partitions the tasks into groups so that the tasks in each group are allocated
independently of the other groups. Tasks in a group of size at least two are
allocated by an affine minimizer and tasks in singleton groups by a
task-independent mechanism. This characterization is about all truthful
mechanisms, including those with unbounded approximation ratio.
A direct consequence of this approach is that the approximation ratio of
mechanisms for two players is 2, even for two tasks. In fact, it follows that
for two players, VCG is the unique algorithm with optimal approximation 2.
This characterization provides some support that any decisive truthful
mechanism (for 3 or more players) partitions the tasks into groups some of
which are allocated by affine minimizers, while the rest are allocated by a
threshold mechanism (in which a task is allocated to a player when it is below
a threshold value which depends only on the values of the other players). We
also show here that the class of threshold mechanisms is identical to the class
of additive mechanisms.Comment: 20 pages, 4 figures, ESA'0
Bribeproof mechanisms for two-values domains
Schummer (Journal of Economic Theory 2000) introduced the concept of
bribeproof mechanism which, in a context where monetary transfer between agents
is possible, requires that manipulations through bribes are ruled out.
Unfortunately, in many domains, the only bribeproof mechanisms are the trivial
ones which return a fixed outcome.
This work presents one of the few constructions of non-trivial bribeproof
mechanisms for these quasi-linear environments. Though the suggested
construction applies to rather restricted domains, the results obtained are
tight: For several natural problems, the method yields the only possible
bribeproof mechanism and no such mechanism is possible on more general domains.Comment: Extended abstract accepted to SAGT 2016. This ArXiv version corrects
typos in the proofs of Theorem 7 and Claims 28-29 of prior ArXiv versio
Prior-Independent Mechanisms for Scheduling
We study the makespan minimization problem with unrelated selfish machines
under the assumption that job sizes are stochastic. We design simple truthful
mechanisms that under various distributional assumptions provide constant and
sublogarithmic approximations to expected makespan. Our mechanisms are
prior-independent in that they do not rely on knowledge of the job size
distributions. Prior-independent approximation mechanisms have been previously
studied for the objective of revenue maximization [Dhangwatnotai, Roughgarden
and Yan'10, Devanur, Hartline, Karlin and Nguyen'11, Roughgarden, Talgam-Cohen
and Yan'12]. In contrast to our results, in prior-free settings no truthful
anonymous deterministic mechanism for the makespan objective can provide a
sublinear approximation [Ashlagi, Dobzinski and Lavi'09].Comment: This paper will appear in Proceedings of the ACM Symposium on Theory
of Computing 2013 (STOC'13
Truthful Online Scheduling with Commitments
We study online mechanisms for preemptive scheduling with deadlines, with the goal of maximizing the total value of completed jobs. This problem is fundamental to deadline-aware cloud scheduling, but there are strong lower bounds even for the algorithmic problem without incentive constraints. However, these lower bounds can be circumvented under the natural assumption of deadline slackness, i.e., that there is a guaranteed lower bound s > 1 on the ratio between a job's size and the time window in which it can be executed. In this paper, we construct a truthful scheduling mechanism with a constant competitive ratio, given slackness s > 1. Furthermore, we show that if s is large enough then we can construct a mechanism that also satisfies a commitment property: it can be determined whether or not a job will finish, and the requisite payment if so, well in advance of each job's deadline. This is notable because, in practice, users with strict deadlines may find it unacceptable to discover only very close to their deadline that their job has been rejected