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arXiv 2103.13089cs.GTcs.DS
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单样本Prophet不等式的再研究

Single-Sample Prophet Inequalities Revisited

Constantine Caramanis, Matthew Faw, Orestis Papadigenopoulos, Emmanouil Pountourakis

摘要:

在有限信息制度下对预言者不平等问题的研究是由Azar等人发起的。[SODA'14]在追求先验独立的标价机制中。正如他们所示,$O(1)$ -竞争政策是可以实现的,只使用一个单一的样本,从每个代理的分布。他们的结果中有一个值得注意的部分依赖于减少单样本先知不平等(SSPI)的设计,顺序遗忘秘书(OOS)的政策。上述减少是以没有充分利用现有样品为代价的。然而,到目前为止,这基本上是证明许多组合集的SSPI的唯一方法。最近,Rubinstein等人[ITCS'20]给出了一个令人惊讶的简单算法,该算法实现了单选SSPI问题$-$的最优竞争比,这是通过将其归约为秘书问题而无法获得的结果。出于这种差异,我们直接研究简单的SSPI政策的竞争力,而不呼吁从OOS文献的结果。在这个方向上,我们首先开发了一个框架,用于分析针对贪婪的先知解决方案的政策。使用这个框架,我们得到的第一个SSPI一般(非二分)匹配环境,以及改进的竞争比横向和截断分区拟阵。其次,出于观察,许多OOS政策拟阵分解成独立的秩$1$的情况下,我们提供了一个元定理,适用于任何拟阵满足此分区属性的问题。利用Rubinstein等人最近的结果,我们获得了改进的竞争性保证(大多数由$2$的一个因素)的减少Azar等人捕获的拟阵的数量。最后,我们讨论了我们的SSPI的应用程序的多维有限的信息设置与改进的收入和福利保证的机制的设计。

英文摘要:

The study of the prophet inequality problem in the limited information regime was initiated by Azar et al. [SODA'14] in the pursuit of prior-independent posted-price mechanisms. As they show, $O(1)$-competitive policies are achievable using only a single sample from the distribution of each agent. A notable portion of their results relies on reducing the design of single-sample prophet inequalities (SSPIs) to that of order-oblivious secretary (OOS) policies. The above reduction comes at the cost of not fully utilizing the available samples. However, to date, this is essentially the only method for proving SSPIs for many combinatorial sets. Very recently, Rubinstein et al. [ITCS'20] give a surprisingly simple algorithm which achieves the optimal competitive ratio for the single-choice SSPI problem $-$ a result which is unobtainable going through the reduction to secretary problems. Motivated by this discrepancy, we study the competitiveness of simple SSPI policies directly, without appealing to results from OOS literature. In this direction, we first develop a framework for analyzing policies against a greedy-like prophet solution. Using this framework, we obtain the first SSPI for general (non-bipartite) matching environments, as well as improved competitive ratios for transversal and truncated partition matroids. Second, motivated by the observation that many OOS policies for matroids decompose the problem into independent rank-$1$ instances, we provide a meta-theorem which applies to any matroid satisfying this partition property. Leveraging the recent results by Rubinstein et al., we obtain improved competitive guarantees (most by a factor of $2$) for a number of matroids captured by the reduction of Azar et al. Finally, we discuss applications of our SSPIs to the design of mechanisms for multi-dimensional limited information settings with improved revenue and welfare guarantees.

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