When should you press the reload button?

While surfing on the Internet, you may have observed the following. If a webpage takes a long time to download and you press the reload button then often the page promptly appears on your screen. Hence, the download was not hindered by congestion — then you’d better try again later — but by some other cause.\ud If you do not know if some cause (like congestion) may hinder your download then what is a good strategy? When should you cancel the download and when should you press the reload button? Should you press it immediately or should you wait for a while? And how long should you wait before cancelling the download? We analyze these issues in this article, which is a non-technical impression of the paper “Efficiency of Repeated Network Interactions” [4] by Judith Timmer (UT) and Michel Mandjes (UvA).\u

The effects of win-win conditions on revenue-sharing contracts

This paper studies revenue-sharing contracts in distribution chains in the presence of win-win conditions. Revenue-sharing contracts are a mechanism to coordinate the firms in a distribution chain. Under these contracts the retailer shares its revenue with the supplier in exchange for a lower wholesale price. The win-win conditions are natural conditions requiring that the profit of any firm may not decrease after implementing the revenue-sharing contract. If these conditions are not met, that is, if at least one firm is confronted with decreased profits, the firms will not agree upon signing the contract and the revenue-sharing contract will not be implemented. We show that the win-win conditions result in a smaller range of contracts being offered by the supplier. More important, in case of multiple competing retailers there may be no revenue-sharing contract satisfying these conditions. Hence, in the presence of win-win conditions revenue-sharing contracts are not suitable for distribution chains with a supplier and multiple competing retailers. For these chains we present a simple alternative coordination mechanism that coordinates the chain and satisfies all win-win conditions. \u

The Compromise Value for Cooperative Games with Random Payoffs

AMS classification: 90D12;cooperative games

Coordination mechanisms for inventory control in three-echelon serial and distribution systems

This paper is concerned with the coordination of inventory control in three-echelon serial and distribution systems under decentralized control. All installations in these supply chains track echelon inventories. Under decentralized control the installations will decide upon base stock levels that minimize their own inventory costs. In general these levels do not coincide with the optimal base stock levels in the global optimum of the chain under centralized control. Hence, the total cost under decentralized control is larger than under centralized control. To remove this cost inefficiency, two simple coordination mechanisms are presented: one for serial systems and one for distribution systems. Both mechanisms are initiated by the most downstream installation(s). The upstream installation increases its base stock level while the downstream installation compensates the upstream one for the increase of costs and provides it with a part of its gain from coordination. It is shown that both coordination mechanisms result in the global optimum of the chain being the unique Nash equilibrium of the corresponding strategic game. Furthermore, all installations agree upon the use of these mechanisms because they result in lower costs per installation. The practical implementation of these mechanisms is discussed. \u

Robust Dynamic Cooperative Games

Classical cooperative game theory is no longer a suitable tool for those situations where the values of coalitions are not known with certainty. Recent works address situations where the values of coalitions are modelled by random variables. In this work we still consider the values of coalitions as uncertain, but model them as unknown but bounded disturbances. We do not focus on solving a specific game, but rather consider a family of games described by a polyhedron: each point in the polyhedron is a vector of coalitions’ values and corresponds to a specific game. We consider a dynamic context where while we know with certainty the average value of each coalition on the long run, at each time such a value is unknown and fluctuates within the bounded polyhedron. Then, it makes sense to define “robust” allocation rules, i.e., allocation rules that bound, within a pre- defined threshold, a so-called complaint vector while guaranteeing a certain average (over time) allocation vector. We also present as motivating example a joint replenishment application

Cooperation and profit allocation in distribution chains

We study the coordination of actions and the allocation of profit in distribution chains under decentralized control. We consider distribution chains in which a single supplier supplies goods for replenishment of stocks of several retailers who, in turn, sell these goods to their own separate markets. The goal of the supplier and the retailers is to maximize their individual profits. Since the optimal joint profit under centralized control is larger than the sum of the individual optimal profits under decentralized control, cooperation among firms by means of coordination of actions may improve individual profits. The effects of cooperation are studied by means of cooperative games. For each distribution chain we define a corresponding cooperative game and study its properties. Among others we show that such games are balanced. Based on the nice core structure a stable solution concept for these games is proposed and its properties are interpreted in terms of the underlying distribution chain. \u

The Compromise Value for Cooperative Games with Random Payoffs

AMS classification: 90D12;

Compensations in Information Collecting Situations

How to compensate people who provide relevant information to a decision-maker who faces uncertainty?This paper suggests some compensation rules.These are studied both in a cooperative and a noncooperative environment.information;game theory;decision making;uncertainty

Linear Transformation of Products: Games and Economies

AMS classifications: 90A15, 90D12.linear transformation;cooperative games;economies;price equilibria

On Three Shapley-Like Solutions for Cooperative Games with Random Payoffs

AMS classification: 90D12.cooperative games;random variables;Shapley values