Sharif Digital Repository

We study the extent to which decentralized cost-sharing protocols can achieve good price of anarchy (PoA) bounds in network cost-sharing games with nagents. We focus on the model of resource-aware protocols, where the designer has prior access to the network structure and can also increase the total cost of an edge (overcharging), and we study classes of games with concave or convex cost functions. We first consider concave cost functions and our main result is a cost-sharing protocol for symmetric games on directed acyclic graphs that achieves a PoA of 2+ϵ for some arbitrary small positive ϵ, which improves to 1+ϵ for games with at least two players. We also achieve a PoA of 1 for... 

We study Nash equilibria in the setting of network creation games introduced recently by Fabrikant, Luthra, Maneva, Papadimitriou and Shenker. In this game we have a set of selfish node players, each creating some incident links, and the goal is to minimize times the cost of the created links plus sum of the distances to all other players. Fabrikant et al. proved an upper bound O(p ) on the price of anarchy, i.e., the relative cost of the lack of coordination. Albers, Eilts, Even-Dar, Mansour, and Roditty show that the price of anarchy is constant for = O(pn) and for ≥ 12 n [dlg] n, and that the price of anarchy is 15 1 + (min{α 2/n , n2 })1/3 for any . The latter bound shows the first... 

Consider a scenario in which several agents are located in the Euclidean space, and the agents want to create a network in which everyone has fast access to all or some other agents. Geometric t-spanners are examples of such a network providing fast connections between the nodes of the network for some fixed value t, i.e. the length of the shortest path between any two nodes in the network is at most t times their Euclidean distance. Geometric t-spanners have been extensively studied in the area of computational geometry where they are created by a central authority. In this paper, we investigate a situation in which selfish agents want to create such a network in the absence of a central... 

We study Nash equilibria in the setting of network creation games introduced recently by Fabrikant, Luthra, Maneva, Papadimitriou, and Shenker. In this game we have a set of selfish node players, each creating some incident links, and the goal is to minimize α times the cost of the created links plus sum of the distances to all other players. Fabrikant et al. proved an upper bound O(√α) on the price of anarchy: the relative cost of the lack of coordination. Albers, Eilts, Even-Dar, Mansour, and Roditty show that the price of anarchy is constant for α = O(√n) and for α ≥ 12n[lgn], and that the price of anarchy is 15(1 + (min{α/n, n 2/alpha;}) 1/3) for any α. The latter bound shows the first...