arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.01285cs.LGcs.CL
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样例引导的主动学习

Exemplar Guided Active Learning

AI21 Labs(AI21实验室);cs.ubc.ca(英属哥伦比亚大学计算机科学系);ai21.com(AI21公司(注:原文本中“ai21.com”为机构相关邮箱域名,推测为AI21 Labs的关联域名,但根据提取规则,严格以明确机构名为准,此处主要明确机构为AI21 Labs,原文本中“cs.ubc.ca”为邮箱后缀,可能关联UBC,但需确认是否为机构。根据提取规则,“只提取作者的所属机构”,此处作者的Affiliation均为AI21 Labs,其他为邮箱域名,非机构,因此仅保留AI21 Labs。)修正:严格按原文,所有作者的Affiliation字段均为“AI21 Labs”,其他为邮箱信息,非机构。因此正确输出应为{)

Jason Hartford, Kevin Leyton-Brown, Hadas Raviv, Dan Padnos, Shahar Lev, Barak Lenz

摘要:

我们考虑明智地使用有限的预算来标记一个大型未标记数据集的一个小子集的问题。我们的动机是词义消歧的NLP问题。对于任何单词,我们都有一组来自知识库的候选标签,但标签集并不一定代表数据中发生的事情:知识库中可能存在很少出现在语料库中的标签,因为这个意义在现代英语中很少见;相反,可能存在真正的标签,但在我们的知识库中不存在。我们的目标是获得一个分类器,执行尽可能的例子,每个“常见的类”,发生的频率高于一个给定的阈值在未标记的集合,同时注释尽可能少的例子,从“罕见的类”,其标签发生的频率低于这个频率。挑战在于,我们不知道哪些标签是常见的,哪些是罕见的,并且真实的标签分布可能会表现出极端的倾斜。我们描述了一种主动学习方法,该方法(1)通过利用现代语言模型提供的上下文嵌入空间来显式搜索稀有类,以及(2)结合了一个停止规则,一旦我们证明它们以高概率出现在我们的目标阈值以下,则忽略类。我们证明,我们的算法只需要花费比一个假设的方法,知道所有真正的标签频率,并通过实验表明,结合自动搜索可以显着减少所需的样本数量,以达到目标的准确性水平。

英文摘要:

We consider the problem of wisely using a limited budget to label a small subset of a large unlabeled dataset. We are motivated by the NLP problem of word sense disambiguation. For any word, we have a set of candidate labels from a knowledge base, but the label set is not necessarily representative of what occurs in the data: there may exist labels in the knowledge base that very rarely occur in the corpus because the sense is rare in modern English; and conversely there may exist true labels that do not exist in our knowledge base. Our aim is to obtain a classifier that performs as well as possible on examples of each "common class" that occurs with frequency above a given threshold in the unlabeled set while annotating as few examples as possible from "rare classes" whose labels occur with less than this frequency. The challenge is that we are not informed which labels are common and which are rare, and the true label distribution may exhibit extreme skew. We describe an active learning approach that (1) explicitly searches for rare classes by leveraging the contextual embedding spaces provided by modern language models, and (2) incorporates a stopping rule that ignores classes once we prove that they occur below our target threshold with high probability. We prove that our algorithm only costs logarithmically more than a hypothetical approach that knows all true label frequencies and show experimentally that incorporating automated search can significantly reduce the number of samples needed to reach target accuracy levels.

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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