Given pairwise comparisons between multiple items, how to rank them so that the ranking matches the observations? This problem, known as rank aggregation, has found many applications in sports, recommendation systems, and other web applications. As it is generally NP-hard to find a global ranking that minimizes the mismatch (known as the Kemeny optimization), we focus on the Erd\"os-R\'enyi outliers (ERO) model for this ranking problem. Here, each pairwise comparison is a corrupted copy of the true score difference. We investigate spectral ranking algorithms that are based on unnormalized and normalized data matrices. The key is to understand their performance in recovering the underlying scores of each item from the observed data. This reduces to deriving an entry-wise perturbation error bound between the top eigenvectors of the unnormalized/normalized data matrix and its population counterpart. By using the leave-one-out technique, we provide a sharper $\ell_{\infty}$-norm perturbation bound of the eigenvectors and also derive an error bound on the maximum displacement for each item, with only $\Omega(n\log n)$ samples. Our theoretical analysis improves upon the state-of-the-art results in terms of sample complexity, and our numerical experiments confirm these theoretical findings.

给定多个项目之间的成对比较，如何对它们进行排名，以使得排名与观察结果相匹配？本研究关注基于Erdos-Renyi异常值（ERO）模型的排名问题，在该问题中，每个成对比较都是真实分数差异的损坏副本。通过研究基于非归一化和归一化数据矩阵的谱排名算法，我们提供了每个项目从观察数据中恢复出其潜在分数的性能，并得出了非归一化/归一化数据矩阵的最大特征向量与其总体对应物之间的逐项扰动误差界限。通过留一法技术，我们提供了更精确的最大特征向量的l∞范数扰动界限，并在只有Ω(nlogn)个样本的情况下导出了每个项目的最大偏移误差界限。理论分析在样本复杂度方面改进了现有技术的结果，并通过数值实验验证了这些理论发现。

通过谱方法改进的排名聚合的理论保证