188,196 research outputs found
The Complexity of Matching Games: A Survey
Matching games naturally generalize assignment games, a well-known class of
cooperative games. Interest in matching games has grown recently due to some
breakthrough results and new applications. This state-of-the-art survey
provides an overview of matching games and extensions, such as -matching
games and partitioned matching games; the latter originating from the emerging
area of international kidney exchange. In this survey we focus on computational
complexity aspects of various game-theoretical solution concepts, such as the
core, nucleolus and Shapley value, when the input is restricted to some
(generalized) matching game
Complexity of Stability-based Solution Concepts in Multi-issue and MC-net Cooperative Games
ABSTRACT MC-nets constitute a natural compact representation scheme for cooperative games in multiagent systems. In this paper, we study the complexity of several natural computational problems that concern solution concepts such as the core, the least core and the nucleolus. We characterize the complexity of these problems for a variety of subclasses of MC-nets, also considering constraints on the game such as superadditivity (where appropriate). Many of our hardness results are derived from a hardness result that we establish for a class of multi-issue cooperative games (SILT games); we suspect that this hardness result can also be used to prove hardness for other representation schemes
Non-coherent successive relaying and cooperation: principles, designs, and applications
Cooperative communication is capable of forming a virtual antenna array for each node (user) in a network by allowing the nodes (users) to relay the messages of others to the destination. Such a relay aided network may be viewed as a distributed multiple-input multiple-output (MIMO) system relying on the spatially distributed single antennas of the cooperating mobiles, which avoids the correlation of the antenna elements routinely encountered in conventional MIMO systems and hence attains the maximum achievable diversity gain. Therefore, the family of cooperative communication techniques may be regarded as a potential solution for future wireless networks. However, constrained by the half-duplex transmit/receive mode of most practical transceivers, the cooperative networks may impose a severe 50% throughput loss. As a remedy, successive relaying can be employed, which is capable of mimicking a full-duplex relay and thereby recovering much of the 50% throughput loss. Furthermore, for the sake of bypassing power-hungry and potentially excessive-complexity channel estimation, noncoherent detection techniques may be employed for multiple-antenna aided systems, because estimating all the associated channels may become unrealistic. Explicitly, the mobile-stations acting as relays cannot be realistically expected to estimate the source-to-relay channels. In order to motivate further research on noncoherent successive relaying aided systems, a comprehensive review of its basic concepts, fundamental principles, practical transceiver designs and open challenges is provide
A Case for Cooperative Cloud Intermediaries for Small and Medium-Sized Enterprises
Cloud computing is a new and increasingly popular form of IT outsourcing. It implies that a cloud service provider offers very standardized abstract IT services which are accessed by a user over the Internet. While cloud services are supposed to be very beneficial for small and medium-sized enterprises, the adoption of such services has been low in this group, among other reasons because of high complexity of the cloud market and trust concerns. This paper motivates the notion of cooperative cloud intermediaries as a solution for these concerns by building on well-known concepts: transaction cost theory, agency theory, the notion of intermediaries in electronic markets and the cooperative paradigm. We derive our solution in detail and show its viability in theory
Cooperative Games with Bounded Dependency Degree
Cooperative games provide a framework to study cooperation among
self-interested agents. They offer a number of solution concepts describing how
the outcome of the cooperation should be shared among the players.
Unfortunately, computational problems associated with many of these solution
concepts tend to be intractable---NP-hard or worse. In this paper, we
incorporate complexity measures recently proposed by Feige and Izsak (2013),
called dependency degree and supermodular degree, into the complexity analysis
of cooperative games. We show that many computational problems for cooperative
games become tractable for games whose dependency degree or supermodular degree
are bounded. In particular, we prove that simple games admit efficient
algorithms for various solution concepts when the supermodular degree is small;
further, we show that computing the Shapley value is always in FPT with respect
to the dependency degree. Finally, we note that, while determining the
dependency among players is computationally hard, there are efficient
algorithms for special classes of games.Comment: 10 pages, full version of accepted AAAI-18 pape
Learning Cooperative Games
This paper explores a PAC (probably approximately correct) learning model in
cooperative games. Specifically, we are given random samples of coalitions
and their values, taken from some unknown cooperative game; can we predict the
values of unseen coalitions? We study the PAC learnability of several
well-known classes of cooperative games, such as network flow games, threshold
task games, and induced subgraph games. We also establish a novel connection
between PAC learnability and core stability: for games that are efficiently
learnable, it is possible to find payoff divisions that are likely to be stable
using a polynomial number of samples.Comment: accepted to IJCAI 201
Cooperation and Competition when Bidding for Complex Projects: Centralized and Decentralized Perspectives
To successfully complete a complex project, be it a construction of an
airport or of a backbone IT system, agents (companies or individuals) must form
a team having required competences and resources. A team can be formed either
by the project issuer based on individual agents' offers (centralized
formation); or by the agents themselves (decentralized formation) bidding for a
project as a consortium---in that case many feasible teams compete for the
contract. We investigate rational strategies of the agents (what salary should
they ask? with whom should they team up?). We propose concepts to characterize
the stability of the winning teams and study their computational complexity
Variance Allocation and Shapley Value
Motivated by the problem of utility allocation in a portfolio under a
Markowitz mean-variance choice paradigm, we propose an allocation criterion for
the variance of the sum of possibly dependent random variables. This
criterion, the Shapley value, requires to translate the problem into a
cooperative game. The Shapley value has nice properties, but, in general, is
computationally demanding. The main result of this paper shows that in our
particular case the Shapley value has a very simple form that can be easily
computed. The same criterion is used also to allocate the standard deviation of
the sum of random variables and a conjecture about the relation of the
values in the two games is formulated.Comment: 20page
Computing the Least-core and Nucleolus for Threshold Cardinality Matching Games
Cooperative games provide a framework for fair and stable profit allocation
in multi-agent systems. \emph{Core}, \emph{least-core} and \emph{nucleolus} are
such solution concepts that characterize stability of cooperation. In this
paper, we study the algorithmic issues on the least-core and nucleolus of
threshold cardinality matching games (TCMG). A TCMG is defined on a graph
and a threshold , in which the player set is and the profit of
a coalition is 1 if the size of a maximum matching in
meets or exceeds , and 0 otherwise. We first show that for a TCMG, the
problems of computing least-core value, finding and verifying least-core payoff
are all polynomial time solvable. We also provide a general characterization of
the least core for a large class of TCMG. Next, based on Gallai-Edmonds
Decomposition in matching theory, we give a concise formulation of the
nucleolus for a typical case of TCMG which the threshold equals . When
the threshold is relevant to the input size, we prove that the nucleolus
can be obtained in polynomial time in bipartite graphs and graphs with a
perfect matching
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