2,381 research outputs found
A Survey of Models of Network Formation: Stability and Efficiency
I survey the recent literature on the formation of networks. I provide definitions of network games, a number of examples of models from the literature, and discuss some of what is known about the (in)compatibility of overall societal welfare with individual incentives to form and sever links
Egalitarianism in the rank aggregation problem: a new dimension for democracy
Winner selection by majority, in an election between two candidates, is the
only rule compatible with democratic principles. Instead, when the candidates
are three or more and the voters rank candidates in order of preference, there
are no univocal criteria for the selection of the winning (consensus) ranking
and the outcome is known to depend sensibly on the adopted rule. Building upon
XVIII century Condorcet theory, whose idea was to maximize total voter
satisfaction, we propose here the addition of a new basic principle (dimension)
to guide the selection: satisfaction should be distributed among voters as
equally as possible. With this new criterion we identify an optimal set of
rankings. They range from the Condorcet solution to the one which is the most
egalitarian with respect to the voters. We show that highly egalitarian
rankings have the important property to be more stable with respect to
fluctuations and that classical consensus rankings (Copeland, Tideman, Schulze)
often turn out to be non optimal. The new dimension we have introduced
provides, when used together with that of Condorcet, a clear classification of
all the possible rankings. By increasing awareness in selecting a consensus
ranking our method may lead to social choices which are more egalitarian
compared to those achieved by presently available voting systems.Comment: 18 pages, 14 page appendix, RateIt Web Tool:
http://www.sapienzaapps.it/rateit.php, RankIt Android mobile application:
https://play.google.com/store/apps/details?id=sapienza.informatica.rankit.
Appears in Quality & Quantity, 10 Apr 2015, Online Firs
Strongly Stable Networks
We analyze the formation of networks among individuals. In particular, we examine the existence of networks that are stable against changes in links by any coalition of individuals. We show that to investigate the existence of such strongly stable networks one can restrict focus on a component-wise egalitarian allocation of value. We show that when such strongly stable networks exist they coincide with the set of efficient networks (those maximizing the total productive value). We show that the existence of strongly stable networks is equivalent to core existence in a derived cooperative game and use that result to characterize the class of value functions for which there exist strongly stable networks via a ``top convexity'' condition on the value function on networks. We also consider a variation on strong stability where players can make side payments, and examine situations where value functions may be non- anonymous -- depending on player labels.Networks, Network formation, strong stability, core, strong equilibrium, efficiency
The Stability and Efficiency of Economic and Social Networks
This paper studies the formation of networks among individuals. The focus is on the compatibility of overall societal welfare with individual incentives to form and sever links. The paper reviews and synthesizes some previous results on the subject, and also provides new results on the existence of pairwise-stable networks and the relationship between pairwise stable and efficient networks in a variety of contexts and under several definitions of efficiency.networks, network formation, stability, efficiency, social networks
Connections among farsighted agents
farsighted players, stability, efficiency, connections model, buyer-seller networks
Connections Among Farsighted Agents
We study the stability of social and economic networks when players are farsighted. In particular, we examine whether the networks formed by farsighted players are different from those formed by myopic players. We adopt Herings, Mauleon and Vannetelboschâs (Games and Economic Behavior, forthcoming) notion of pairwise farsightedly stable set. We first investigate in some classical models of social and economic networks whether the pairwise farsightedly stable sets of networks coincide with the set of pairwise (myopically) stable networks and the set of strongly efficient networks. We then provide some primitive conditions on value functions and allocation rules so that the set of strongly efficient networks is the unique pairwise farsightedly stable set. Under the componentwise egalitarian allocation rule, the set of strongly efficient networks and the set of pairwise (myopically) stable networks that are immune to coalitional deviations are the unique pairwise farsightedly stable set if and only if the value function is top convex.Farsighted Players, Stability, Efficiency, Connections Model, Buyerseller Networks
Pairwise Kidney Exchange
The theoretical literature on exchange of indivisible goods finds natural application in organizing the exchange of live donor kidneys for transplant. However, in kidney exchange, there are constraints on the size of feasible exchanges. Initially, kidney exchanges are likely to be pairwise exchanges, between just two patient-donor pairs, as these are logistically simpler than larger exchanges. Furthermore, the experience of many American surgeons suggests to them that preferences over kidneys are approximately 0-1, i.e. that patients and surgeons should be largely indifferent among healthy donors whose kidneys are compatible with the patient. This is because, in the United States, transplants of compatible live kidneys have about equal graft survival probabilities, regardless of the closeness of tissue types between patient and donor. We show that, although the pairwise constraint eliminates some potential exchanges, there is a wide class of constrained-efficient mechanisms that are strategy-proof when patient-donor pairs and surgeons have 0-1 preferences. This class of mechanisms includes deterministic mechanisms that would accomodate the kinds of priority setting that organ banks currently use to allocate cadaver organs, as well as stochastic mechanisms that allow distributive justice issues to be
Selection Bias in News Coverage: Learning it, Fighting it
News entities must select and filter the coverage they broadcast through
their respective channels since the set of world events is too large to be
treated exhaustively. The subjective nature of this filtering induces biases
due to, among other things, resource constraints, editorial guidelines,
ideological affinities, or even the fragmented nature of the information at a
journalist's disposal. The magnitude and direction of these biases are,
however, widely unknown. The absence of ground truth, the sheer size of the
event space, or the lack of an exhaustive set of absolute features to measure
make it difficult to observe the bias directly, to characterize the leaning's
nature and to factor it out to ensure a neutral coverage of the news. In this
work, we introduce a methodology to capture the latent structure of media's
decision process on a large scale. Our contribution is multi-fold. First, we
show media coverage to be predictable using personalization techniques, and
evaluate our approach on a large set of events collected from the GDELT
database. We then show that a personalized and parametrized approach not only
exhibits higher accuracy in coverage prediction, but also provides an
interpretable representation of the selection bias. Last, we propose a method
able to select a set of sources by leveraging the latent representation. These
selected sources provide a more diverse and egalitarian coverage, all while
retaining the most actively covered events
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