有界噪声下线性分离器的高效学习Efficient Learning of Linear Separators under Bounded Noise |
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课程网址: | https://videolectures.net/videos/colt2015_urner_linear_separators |
主讲教师: | Ruth Urner |
开课单位: | 信息不详。欢迎您在右侧留言补充。 |
开课时间: | 2025-02-04 |
课程语种: | 英语 |
中文简介: | 我们研究了$\Re^d$中存在有界(即Massart)噪声的线性分离器的可学习性。这是随机分类噪声模型的现实推广,其中对手可以以$\eta(x) \leq \eta$的概率翻转每个示例$x$。我们在$\Re^d$中提供了第一个多项式时间算法,该算法可以在单位球面上均匀分布的噪声模型中学习到任意小的多余误差的线性分离器。虽然在统计学习理论界以更快的收敛速度进行了广泛的研究,但该模型中计算效率高的算法仍然难以捉摸。我们的工作提供了第一个证据,证明人们确实可以在这种现实噪声模型下设计出在多项式时间内实现任意小超额误差的算法,从而开辟了一条新的令人兴奋的研究路线。我们还提供了下界,表明在Massart噪声下,即使在均匀分布下,铰链损失最小化和平均等流行算法也不会导致任意小的过量误差。相反,我们的工作利用了在主动学习的背景下开发的基于边际的技术。因此,我们的算法也是一种主动学习算法,在期望的超额误差$\epsilon$中只有对数依赖关系。 |
课程简介: | We study the learnability of linear separators in $\Re^d$ in the presence of bounded (a.k.a Massart) noise. This is a realistic generalization of the random classification noise model, where the adversary can flip each example $x$ with probability $\eta(x) \leq \eta$. We provide the first polynomial time algorithm that can learn linear separators to arbitrary small excess error in this noise model under the uniform distribution over the unit sphere in $\Re^d$. While widely studied in the statistical learning theory community in the context of getting faster convergence rates, computationally efficient algorithms in this model had remained elusive. Our work provides the first evidence that one can indeed design algorithms achieving arbitrary small excess errors in polynomial time under this realistic noise model and thus opens up a new and exciting line of research. We additionally provide lower bounds showing that popular algorithms such as hinge loss minimization and averaging cannot lead to arbitrary small excess error under Massart noise, even under the uniform distribution. Our work instead, makes use of a margin based technique developed in the context of active learning. As a result, our algorithm is also an active learning algorithm with only a logarithmic dependence in the desired excess error $\epsilon$. |
关 键 词: | 线性分离器:随即分类噪声模型; 统计学 |
课程来源: | 视频讲座网 |
数据采集: | 2025-04-02:zsp |
最后编审: | 2025-04-02:zsp |
阅读次数: | 1 |