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arXiv 2107.06649cs.GTcs.DS
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求解家务劳动近似竞争均衡的多项式时间算法

Polynomial Time Algorithms to Find an Approximate Competitive Equilibrium for Chores

Shant Boodaghians, Bhaskar Ray Chaudhury, Ruta Mehta

摘要:

平等收入竞争均衡(CEEI)被认为是在代理人之间公平有效地分配一组物品的最佳机制之一。在本文中,我们研究的计算CEEI项目时,不喜欢(负价值)的代理人,1齐次和凹效用函数,其中包括线性函数作为一个子情况下的家务。众所周知,即使是线性效用,CEEI的集合也可能是非凸的和不连通的,并且在更一般的交换模型中问题是PPAD困难的。在这些负面的结果相比,我们设计FPTAS:多项式时间算法来计算$ε$ -近似CEEI的运行时间多项式依赖于$1/ε$。我们的算法依赖于最近的表征由于Bogomolnaia等人。(2017)的CEEI集正好是一个非凸最小化问题的KKT点,所有坐标都不为零。由于这种非零约束,朴素的基于梯度的方法无法找到所需的局部最小值,因为它们被吸引到零。我们开发了一种外点方法,该方法在猜测非零KKT点和沿着这些点的支持超平面最大化目标之间交替。我们表明,这个过程必须迅速收敛到一个近似的KKT点,然后可以映射到一个近似的CEEI,这种外部点的方法可能是独立的兴趣。当效用函数为线性时,我们给出了求精确迭代的显式方法,并证明了在多项式时间内可以得到更强形式的近似CEEI。最后,我们注意到,我们的算法扩展到设置不平等的收入(CE),并与线性效用的混合甘露,每个代理可能喜欢(积极的价值)的一些项目和不喜欢(消极的价值)的人。

英文摘要:

Competitive equilibrium with equal income (CEEI) is considered one of the best mechanisms to allocate a set of items among agents fairly and efficiently. In this paper, we study the computation of CEEI when items are chores that are disliked (negatively valued) by agents, under 1-homogeneous and concave utility functions which includes linear functions as a subcase. It is well-known that, even with linear utilities, the set of CEEI may be non-convex and disconnected, and the problem is PPAD-hard in the more general exchange model. In contrast to these negative results, we design FPTAS: A polynomial-time algorithm to compute $ε$-approximate CEEI where the running-time depends polynomially on $1/ε$. Our algorithm relies on the recent characterization due to Bogomolnaia et al.~(2017) of the CEEI set as exactly the KKT points of a non-convex minimization problem that have all coordinates non-zero. Due to this non-zero constraint, naive gradient-based methods fail to find the desired local minima as they are attracted towards zero. We develop an exterior-point method that alternates between guessing non-zero KKT points and maximizing the objective along supporting hyperplanes at these points. We show that this procedure must converge quickly to an approximate KKT point which then can be mapped to an approximate CEEI; this exterior point method may be of independent interest. When utility functions are linear, we give explicit procedures for finding the exact iterates, and as a result show that a stronger form of approximate CEEI can be found in polynomial time. Finally, we note that our algorithm extends to the setting of un-equal incomes (CE), and to mixed manna with linear utilities where each agent may like (positively value) some items and dislike (negatively value) others.

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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