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arXiv 1710.06360stat.ML
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通过Bandit反馈进行良好的手臂识别

Good Arm Identification via Bandit Feedback

Hideaki Kano, Junya Honda, Kentaro Sakamaki, Kentaro Matsuura, Atsuyoshi Nakamura, Masashi Sugiyama

摘要:

我们考虑了一个新的随机多臂强盗问题称为{ \em好臂识别}(GAI),其中一个好臂被定义为一个手臂的预期回报大于或等于一个给定的阈值。GAI是一个纯粹的探索问题,单个智能体重复输出一个手臂的过程,只要它被识别为一个好的,然后确认其他手臂实际上是不好的。GAI的目标是尽量减少每个过程的样本数量。我们发现,GAI面临着一种新的困境,{ \em探索-利用困境的信心},这是不同的困难,从最佳臂识别。因此,GAI算法的有效设计与最佳手臂识别的算法完全不同。我们推导出GAI的样本复杂度的下界,该下界紧到接受错误率$δ$的对数因子$\mathrm{O}(\log \frac{1}δ)$。我们还开发了一个算法,其样本复杂度几乎匹配的下限。我们还证实,我们提出的算法优于天真的算法在合成设置的基础上,传统的强盗问题和类风湿关节炎的临床试验研究。

英文摘要:

We consider a novel stochastic multi-armed bandit problem called {\em good arm identification} (GAI), where a good arm is defined as an arm with expected reward greater than or equal to a given threshold. GAI is a pure-exploration problem that a single agent repeats a process of outputting an arm as soon as it is identified as a good one before confirming the other arms are actually not good. The objective of GAI is to minimize the number of samples for each process. We find that GAI faces a new kind of dilemma, the {\em exploration-exploitation dilemma of confidence}, which is different difficulty from the best arm identification. As a result, an efficient design of algorithms for GAI is quite different from that for the best arm identification. We derive a lower bound on the sample complexity of GAI that is tight up to the logarithmic factor $\mathrm{O}(\log \frac{1}δ)$ for acceptance error rate $δ$. We also develop an algorithm whose sample complexity almost matches the lower bound. We also confirm experimentally that our proposed algorithm outperforms naive algorithms in synthetic settings based on a conventional bandit problem and clinical trial researches for rheumatoid arthritis.

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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