arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1111.0554cs.GT
收藏

有界预算网络创造博弈

On a Bounded Budget Network Creation Game

Shayan Ehsani, Saber Shokat Fadaee, MohammadAmin Fazli, Abbas Mehrabian, Sina Sadeghian Sadeghabad, MohammadAli Safari, Morteza Saghafian

摘要:

我们考虑一个网络创建游戏,其中每个玩家(顶点)有一个固定的预算,以建立链接到其他玩家。在我们的模型中,每个链接都有单价,每个代理都试图最小化其成本,这是它的局部直径或它到所创建网络的(无向)底层图中其他参与者的总距离。研究了两个版本的博弈:在MAX版本中,一个顶点的代价是该顶点与其他顶点之间的最大距离;在SUM版本中,一个顶点的代价是该顶点与其他顶点之间的距离之和。我们证明了在这两个版本中存在纯纳什均衡,但找到一个顶点的最佳对策的问题是NP-难的。我们把所创建的网络的社会成本作为它的直径,接下来我们研究了在各种情况下具有n个顶点的平衡图的最大可能直径。当局中人的预算之和为n-1时,均衡图总是树,并且证明了在MAX和SUM两种情况下,均衡图的最大直径分别为Theta(n)和Theta(log n).当每个顶点都有单位预算(即只能与一个顶点建立链接)时,任何版本的平衡图的直径都是Theta(1)。我们给出了MAX版本的平衡图的例子,使得所有顶点都有正预算,但直径是Omega(sqrt(log n))。这个有趣的(也许是违反直觉的)结果表明,增加预算可能会增加平衡图的直径,从而恶化网络结构。然后证明了SUM版本中的每个平衡图的直径为2^O(sqrt(log n)).最后,我们证明了如果每个局中人的预算至少是k,那么SUM版本中的每个均衡图都是k-连通的或直径小于4。

英文摘要:

We consider a network creation game in which each player (vertex) has a fixed budget to establish links to other players. In our model, each link has unit price and each agent tries to minimize its cost, which is either its local diameter or its total distance to other players in the (undirected) underlying graph of the created network. Two versions of the game are studied: in the MAX version, the cost incurred to a vertex is the maximum distance between the vertex and other vertices, and in the SUM version, the cost incurred to a vertex is the sum of distances between the vertex and other vertices. We prove that in both versions pure Nash equilibria exist, but the problem of finding the best response of a vertex is NP-hard. We take the social cost of the created network to be its diameter, and next we study the maximum possible diameter of an equilibrium graph with n vertices in various cases. When the sum of players' budgets is n-1, the equilibrium graphs are always trees, and we prove that their maximum diameter is Theta(n) and Theta(log n) in MAX and SUM versions, respectively. When each vertex has unit budget (i.e. can establish link to just one vertex), the diameter of any equilibrium graph in either version is Theta(1). We give examples of equilibrium graphs in the MAX version, such that all vertices have positive budgets and yet the diameter is Omega(sqrt(log n)). This interesting (and perhaps counter-intuitive) result shows that increasing the budgets may increase the diameter of equilibrium graphs and hence deteriorate the network structure. Then we prove that every equilibrium graph in the SUM version has diameter 2^O(sqrt(log n)). Finally, we show that if the budget of each player is at least k, then every equilibrium graph in the SUM version is k-connected or has diameter smaller than 4.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑