有监督的分类技术使用培训样本来学习具有小预期0-1损失(错误概率)的分类规则。常规方法可以通过使用替代损失而不是0-1损失并考虑特定的规则家族(假设类别)来实现可拖动学习并提供样本外的概括。本文介绍了Minimax风险分类器(MRCS),该分类器将最差的0-1损失比一般分类规则最小化,并在学习时提供严格的绩效保证。我们表明,使用特征内核给出的特征映射非常普遍地一致。本文还提出了MRC学习的有效优化技术,并表明提出的方法可以提供准确的分类以及实践中的紧张性能保证。
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我们开发用于测试两个或多个数据流是否来自同一源的电子变量,更普遍地说,源之间的差异是否大于某些最小效应大小。这些电子变量导致精确的非肌电测试,这些测试仍然是安全的,即在柔性采样场景(例如可选的停止和延续)下,保持其类型错误保证。在特殊情况下,我们的电子变量在替代方面也具有最佳的“增长”特性。虽然构造是通用的,但我们通过K x 2应急表的特殊情况进行了说明,我们还允许在复合替代方案上纳入不同的限制。与模拟中的p值分析和现实世界中的p值分析进行比较,表明电子变量通过其灵活性,通常允许早日停止数据收集,从而保留与经典方法相似的功率,同时还保留了扩展或结合的选项之后数据。
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我们介绍了强大的子组发现的问题,即,找到一个关于一个或多个目标属性的脱颖而出的子集的一组可解释的描述,2)是统计上的鲁棒,并且3)非冗余。许多尝试已经挖掘了局部强壮的子组或解决模式爆炸,但我们是第一个从全球建模角度同时解决这两个挑战的爆炸。首先,我们制定广泛的模型类别的子组列表,即订购的子组,可以组成的单次组和多变量目标,该目标可以由标称或数字变量组成,并且包括其定义中的传统Top-1子组发现。这种新颖的模型类允许我们使用最小描述长度(MDL)原理来形式地形化最佳强大的子组发现,在那里我们分别为标称和数字目标的最佳归一化最大可能性和贝叶斯编码而度假。其次,正如查找最佳子组列表都是NP-Hard,我们提出了SSD ++,一个贪婪的启发式,找到了很好的子组列表,并保证了根据MDL标准的最重要的子组在每次迭代中添加,这被显示为等同于贝叶斯一个样本比例,多项式或子组之间的多项式或T检验,以及数据集边际目标分布以及多假设检测罚款。我们经验上显示了54个数据集,即SSD ++优于先前的子组设置发现方法和子组列表大小。
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我们基于电子价值开发假设检测理论,这是一种与p值不同的证据,允许毫不费力地结合来自常见场景中的几项研究的结果,其中决定执行新研究可能取决于以前的结果。基于E-V值的测试是安全的,即它们在此类可选的延续下保留I型错误保证。我们将增长速率最优性(GRO)定义为可选的连续上下文中的电力模拟,并且我们展示了如何构建GRO E-VARIABLE,以便为复合空缺和替代,强调模型的常规测试问题,并强调具有滋扰参数的模型。 GRO E值采取具有特殊前瞻的贝叶斯因子的形式。我们使用几种经典示例说明了该理论,包括一个样本安全T检验(其中右哈尔前方的右手前锋为GE)和2x2差价表(其中GRE之前与标准前沿不同)。分享渔业,奈曼和杰弗里斯·贝叶斯解释,电子价值观和相应的测试可以提供所有三所学校的追随者可接受的方法。
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Supervised Question Answering systems (QA systems) rely on domain-specific human-labeled data for training. Unsupervised QA systems generate their own question-answer training pairs, typically using secondary knowledge sources to achieve this outcome. Our approach (called PIE-QG) uses Open Information Extraction (OpenIE) to generate synthetic training questions from paraphrased passages and uses the question-answer pairs as training data for a language model for a state-of-the-art QA system based on BERT. Triples in the form of <subject, predicate, object> are extracted from each passage, and questions are formed with subjects (or objects) and predicates while objects (or subjects) are considered as answers. Experimenting on five extractive QA datasets demonstrates that our technique achieves on-par performance with existing state-of-the-art QA systems with the benefit of being trained on an order of magnitude fewer documents and without any recourse to external reference data sources.
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This paper presents a machine learning approach to multidimensional item response theory (MIRT), a class of latent factor models that can be used to model and predict student performance from observed assessment data. Inspired by collaborative filtering, we define a general class of models that includes many MIRT models. We discuss the use of penalized joint maximum likelihood (JML) to estimate individual models and cross-validation to select the best performing model. This model evaluation process can be optimized using batching techniques, such that even sparse large-scale data can be analyzed efficiently. We illustrate our approach with simulated and real data, including an example from a massive open online course (MOOC). The high-dimensional model fit to this large and sparse dataset does not lend itself well to traditional methods of factor interpretation. By analogy to recommender-system applications, we propose an alternative "validation" of the factor model, using auxiliary information about the popularity of items consulted during an open-book exam in the course.
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We introduce Argoverse 2 (AV2) - a collection of three datasets for perception and forecasting research in the self-driving domain. The annotated Sensor Dataset contains 1,000 sequences of multimodal data, encompassing high-resolution imagery from seven ring cameras, and two stereo cameras in addition to lidar point clouds, and 6-DOF map-aligned pose. Sequences contain 3D cuboid annotations for 26 object categories, all of which are sufficiently-sampled to support training and evaluation of 3D perception models. The Lidar Dataset contains 20,000 sequences of unlabeled lidar point clouds and map-aligned pose. This dataset is the largest ever collection of lidar sensor data and supports self-supervised learning and the emerging task of point cloud forecasting. Finally, the Motion Forecasting Dataset contains 250,000 scenarios mined for interesting and challenging interactions between the autonomous vehicle and other actors in each local scene. Models are tasked with the prediction of future motion for "scored actors" in each scenario and are provided with track histories that capture object location, heading, velocity, and category. In all three datasets, each scenario contains its own HD Map with 3D lane and crosswalk geometry - sourced from data captured in six distinct cities. We believe these datasets will support new and existing machine learning research problems in ways that existing datasets do not. All datasets are released under the CC BY-NC-SA 4.0 license.
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The celebrated FedAvg algorithm of McMahan et al. (2017) is based on three components: client sampling (CS), data sampling (DS) and local training (LT). While the first two are reasonably well understood, the third component, whose role is to reduce the number of communication rounds needed to train the model, resisted all attempts at a satisfactory theoretical explanation. Malinovsky et al. (2022) identified four distinct generations of LT methods based on the quality of the provided theoretical communication complexity guarantees. Despite a lot of progress in this area, none of the existing works were able to show that it is theoretically better to employ multiple local gradient-type steps (i.e., to engage in LT) than to rely on a single local gradient-type step only in the important heterogeneous data regime. In a recent breakthrough embodied in their ProxSkip method and its theoretical analysis, Mishchenko et al. (2022) showed that LT indeed leads to provable communication acceleration for arbitrarily heterogeneous data, thus jump-starting the $5^{\rm th}$ generation of LT methods. However, while these latest generation LT methods are compatible with DS, none of them support CS. We resolve this open problem in the affirmative. In order to do so, we had to base our algorithmic development on new algorithmic and theoretical foundations.
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Graph clustering is a fundamental problem in unsupervised learning, with numerous applications in computer science and in analysing real-world data. In many real-world applications, we find that the clusters have a significant high-level structure. This is often overlooked in the design and analysis of graph clustering algorithms which make strong simplifying assumptions about the structure of the graph. This thesis addresses the natural question of whether the structure of clusters can be learned efficiently and describes four new algorithmic results for learning such structure in graphs and hypergraphs. All of the presented theoretical results are extensively evaluated on both synthetic and real-word datasets of different domains, including image classification and segmentation, migration networks, co-authorship networks, and natural language processing. These experimental results demonstrate that the newly developed algorithms are practical, effective, and immediately applicable for learning the structure of clusters in real-world data.
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Selecting the number of topics in LDA models is considered to be a difficult task, for which alternative approaches have been proposed. The performance of the recently developed singular Bayesian information criterion (sBIC) is evaluated and compared to the performance of alternative model selection criteria. The sBIC is a generalization of the standard BIC that can be implemented to singular statistical models. The comparison is based on Monte Carlo simulations and carried out for several alternative settings, varying with respect to the number of topics, the number of documents and the size of documents in the corpora. Performance is measured using different criteria which take into account the correct number of topics, but also whether the relevant topics from the DGPs are identified. Practical recommendations for LDA model selection in applications are derived.
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