DON and Shapley Value for Allocation among Cooperating Agents in a Network: Conditions for Equivalence

2017 ◽  
Vol 5 (2) ◽  
pp. 143-161 ◽  
Author(s):  
Sridhar Mandyam ◽  
Usha Sridhar

In a paper appearing in a recent issue of this journal ( Studies in Microeconomics), the authors explored a new method to allocate a divisible resource efficiently among cooperating agents located at the vertices of a connected undirected network. It was shown in that article that maximizing social welfare of the agents produces Pareto optimal allocations, referred to as dominance over neighbourhood (DON), capturing the notion of dominance over neighbourhood in terms of network degree. In this article, we show that the allocation suggested by the method competes well with current cooperative game-theoretic power centrality measures. We discuss the conditions under which DON turns exactly equivalent to a recent ‘fringe-based’ Shapley Value formulation for fixed networks, raising the possibility of such solutions being both Pareto optimal in a utilitarian social welfare maximization sense as well as fair in the Shapley value sense.

2018 ◽  
Vol 63 ◽  
pp. 145-189 ◽  
Author(s):  
Mateusz K. Tarkowski ◽  
Piotr L. Szczepański ◽  
Tomasz P. Michalak ◽  
Paul Harrenstein ◽  
Michael Wooldridge

Some game-theoretic solution concepts such as the Shapley value and the Banzhaf index have recently gained popularity as measures of node centrality in networks. While this direction of research is promising, the computational problems that surround it are challenging and have largely been left open. To date there are only a few positive results in the literature, which show that some game-theoretic extensions of degree-, closeness- and betweenness-centrality measures are computable in polynomial time, i.e., without the need to enumerate the exponential number of all possible coalitions. In this article, we show that these results can be extended to a much larger class of centrality measures that are based on a family of solution concepts known as semivalues. The family of semivalues includes, among others, the Shapley value and the Banzhaf index. To this end, we present a generic framework for defining game-theoretic network centralities and prove that all centrality measures that can be expressed in this framework are computable in polynomial time. Using our framework, we present a number of new and polynomial-time computable game-theoretic centrality measures.


1973 ◽  
Vol 67 (4) ◽  
pp. 1235-1247 ◽  
Author(s):  
William H. Riker ◽  
Steven J. Brams

Although, conventionally, vote trading in legislatures has been condemned as socially undesirable by both scholars and lay citizens, a recently popular school of scholarship has argued that vote trading improves the traders' welfare in the direction of Pareto-optimal allocations. This essay is an attempt to reconcile the disagreement by showing formally that vote trading does improve the position of the traders but that at the same time trading may impose an external cost on nontraders. In sum, it turns out that sporadic and occasional trading is probably socially beneficial but that systematic trading may engender a paradox of vote trading. This paradox has the property that, while trading is immediately advantageous for the traders, still, when everybody trades, everybody is worse off. Furthermore, vote trading may not produce a stable equilibrium that is Pareto-optimal either for individual members or for coalitions of members.


2018 ◽  
Vol 56 (3) ◽  
pp. 1102-1118 ◽  
Author(s):  
Roger E. A. Farmer

I review The End of Alchemy by Mervyn King, published by W. W. Norton and Company in 2016. I discuss King’s proposed regulatory reform, the “pawnbroker for all seasons” (PFAS), and I compare it to an alternative solution developed in my own work. I argue that unregulated trade in the financial markets will not, in general, lead to Pareto-optimal allocations. As a consequence, solutions like the PFAS that correct problems with existing institutions are likely to be circumvented by the development of new ones. (JEL D81, D82, E44, G01, G18, G28, L51)


Author(s):  
Muhamet Yildiz

We analyze the subgame-perfect equilibria of a game where two agents bargain in order to share the risk in their assets that will pay dividends once at some fixed date. The uncertainty about the size of the dividends is resolved gradually by the payment date and each agent has his own view about how the uncertainty will be resolved. As agents become less uncertain about the dividends, some contracts become unacceptable to some party to such an extent that at the payment date no trade is possible. The set of contracts is assumed to be rich enough to generate all the Pareto-optimal allocations. We show that there exists a unique equilibrium allocation, and it is Pareto-optimal. Immediate agreement is always an equilibrium outcome; under certain conditions, we further show that in equilibrium there cannot be a delay. In this model, the equilibrium shares depend on how the uncertainty is resolved, and an agent can lose when his opponent becomes more risk-averse. Finally, we characterize the conditions under which every Pareto-optimal and individually rational allocation is obtainable via some bargaining procedure as the unique equilibrium outcome.


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