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arXiv 1202.2877cs.GT
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利用协调机制提高自私路由的无政府代价

Improving the Price of Anarchy for Selfish Routing via Coordination Mechanisms

George Christodoulou, Kurt Mehlhorn, Evangelia Pyrga

摘要:

我们重新考虑研究自私路由游戏仿射延迟功能。这类博弈的无政府状态无政府代价取最大值4/3;这个最大值已经在两个平行链接的简单网络中达到,称为庇古网络。我们通过协调机制改进了4/3值。我们增加了网络中边缘的延迟函数,即,如果$\ell_e(x)$是边缘$e$的等待时间函数,则对于所有$x$,我们将其替换为具有$\ell_e(x) \le \hat{\ell}_e(x)$的$\hat{\ell}_e(x)$。然后对手固定一个需求率作为输入。该机制的无政府状态工程无政府代价被定义为最坏情况下修改后的网络中的纳什社会成本与原网络中的最优社会成本之比。形式上,如果$\CM(r)$表示针对速率$r$的修改网络中的最差纳什流的成本,并且$\Copt(r)$表示针对相同速率的原始网络中的最优流的成本,则[ \ePoA = \max_{r \ge 0} \frac{\CM(r)}{\Copt(r)}]。我们首先展示了一个简单的协调机制,实现了任何网络的并行链路工程无政府代价严格小于4/3。对于两个平行连杆的情况,我们的基本机构给出5/4 = 1.25。然后,对于两个平行的链接的情况下,我们描述了一个最佳的机制,其工程无政府代价的无政府状态位于1.191和1.192之间。

英文摘要:

We reconsider the well-studied Selfish Routing game with affine latency functions. The Price of Anarchy for this class of games takes maximum value 4/3; this maximum is attained already for a simple network of two parallel links, known as Pigou's network. We improve upon the value 4/3 by means of Coordination Mechanisms. We increase the latency functions of the edges in the network, i.e., if $\ell_e(x)$ is the latency function of an edge $e$, we replace it by $\hat{\ell}_e(x)$ with $\ell_e(x) \le \hat{\ell}_e(x)$ for all $x$. Then an adversary fixes a demand rate as input. The engineered Price of Anarchy of the mechanism is defined as the worst-case ratio of the Nash social cost in the modified network over the optimal social cost in the original network. Formally, if $\CM(r)$ denotes the cost of the worst Nash flow in the modified network for rate $r$ and $\Copt(r)$ denotes the cost of the optimal flow in the original network for the same rate then [\ePoA = \max_{r \ge 0} \frac{\CM(r)}{\Copt(r)}.] We first exhibit a simple coordination mechanism that achieves for any network of parallel links an engineered Price of Anarchy strictly less than 4/3. For the case of two parallel links our basic mechanism gives 5/4 = 1.25. Then, for the case of two parallel links, we describe an optimal mechanism; its engineered Price of Anarchy lies between 1.191 and 1.192.

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。

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