在多标签学习中，单个数据点与多个目标标签相关联的多任务学习的特定情况，在文献中广泛假定，为了获得最佳准确性，应明确建模标签之间的依赖性。这个前提导致提供的方法的扩散，以学习和预测标签，例如，一个标签的预测会影响对其他标签的预测。即使现在人们承认，在许多情况下，最佳性能并不需要一种依赖模型，但此类模型在某些情况下继续超越独立模型，这暗示了其对其性能的替代解释以外的标签依赖性，而文献仅是文献才是最近开始解开。利用并扩展了最近的发现，我们将多标签学习的原始前提转移到其头上，并在任务标签之间没有任何可衡量的依赖性的情况下特别处理联合模型的问题；例如，当任务标签来自单独的问题域时。我们将洞察力从这项研究转移到建立转移学习方法，该方法挑战了长期以来的假设，即任务的可转移性来自源和目标域或模型之间相似性的测量。这使我们能够设计和测试一种传输学习方法，该方法是模型驱动的，而不是纯粹的数据驱动，并且它是黑匣子和模型不合时式（可以考虑任何基本模型类）。我们表明，从本质上讲，我们可以根据源模型容量创建任务依赖性。我们获得的结果具有重要的含义，并在多标签和转移学习领域为将来的工作提供了明确的方向。

The literature on machine learning in the context of data streams is vast and growing. However, many of the defining assumptions regarding data-stream learning tasks are too strong to hold in practice, or are even contradictory such that they cannot be met in the contexts of supervised learning. Algorithms are chosen and designed based on criteria which are often not clearly stated, for problem settings not clearly defined, tested in unrealistic settings, and/or in isolation from related approaches in the wider literature. This puts into question the potential for real-world impact of many approaches conceived in such contexts, and risks propagating a misguided research focus. We propose to tackle these issues by reformulating the fundamental definitions and settings of supervised data-stream learning with regard to contemporary considerations of concept drift and temporal dependence; and we take a fresh look at what constitutes a supervised data-stream learning task, and a reconsideration of algorithms that may be applied to tackle such tasks. Through and in reflection of this formulation and overview, helped by an informal survey of industrial players dealing with real-world data streams, we provide recommendations. Our main emphasis is that learning from data streams does not impose a single-pass or online-learning approach, or any particular learning regime; and any constraints on memory and time are not specific to streaming. Meanwhile, there exist established techniques for dealing with temporal dependence and concept drift, in other areas of the literature. For the data streams community, we thus encourage a shift in research focus, from dealing with often-artificial constraints and assumptions on the learning mode, to issues such as robustness, privacy, and interpretability which are increasingly relevant to learning in data streams in academic and industrial settings.

The success of machine learning algorithms generally depends on data representation, and we hypothesize that this is because different representations can entangle and hide more or less the different explanatory factors of variation behind the data. Although specific domain knowledge can be used to help design representations, learning with generic priors can also be used, and the quest for AI is motivating the design of more powerful representation-learning algorithms implementing such priors. This paper reviews recent work in the area of unsupervised feature learning and deep learning, covering advances in probabilistic models, auto-encoders, manifold learning, and deep networks. This motivates longer-term unanswered questions about the appropriate objectives for learning good representations, for computing representations (i.e., inference), and the geometrical connections between representation learning, density estimation and manifold learning.

大多数机器学习算法由一个或多个超参数配置，必须仔细选择并且通常会影响性能。为避免耗时和不可递销的手动试验和错误过程来查找性能良好的超参数配置，可以采用各种自动超参数优化（HPO）方法，例如，基于监督机器学习的重新采样误差估计。本文介绍了HPO后，本文审查了重要的HPO方法，如网格或随机搜索，进化算法，贝叶斯优化，超带和赛车。它给出了关于进行HPO的重要选择的实用建议，包括HPO算法本身，性能评估，如何将HPO与ML管道，运行时改进和并行化结合起来。这项工作伴随着附录，其中包含关于R和Python的特定软件包的信息，以及用于特定学习算法的信息和推荐的超参数搜索空间。我们还提供笔记本电脑，这些笔记本展示了这项工作的概念作为补充文件。

这是一门专门针对STEM学生开发的介绍性机器学习课程。我们的目标是为有兴趣的读者提供基础知识，以在自己的项目中使用机器学习，并将自己熟悉术语作为进一步阅读相关文献的基础。在这些讲义中，我们讨论受监督，无监督和强化学习。注释从没有神经网络的机器学习方法的说明开始，例如原理分析，T-SNE，聚类以及线性回归和线性分类器。我们继续介绍基本和先进的神经网络结构，例如密集的进料和常规神经网络，经常性的神经网络，受限的玻尔兹曼机器，（变性）自动编码器，生成的对抗性网络。讨论了潜在空间表示的解释性问题，并使用梦和对抗性攻击的例子。最后一部分致力于加强学习，我们在其中介绍了价值功能和政策学习的基本概念。

预测组合在预测社区中蓬勃发展，近年来，已经成为预测研究和活动主流的一部分。现在，由单个（目标）系列产生的多个预测组合通过整合来自不同来源收集的信息，从而提高准确性，从而减轻了识别单个“最佳”预测的风险。组合方案已从没有估计的简单组合方法演变为涉及时间变化的权重，非线性组合，组件之间的相关性和交叉学习的复杂方法。它们包括结合点预测和结合概率预测。本文提供了有关预测组合的广泛文献的最新评论，并参考可用的开源软件实施。我们讨论了各种方法的潜在和局限性，并突出了这些思想如何随着时间的推移而发展。还调查了有关预测组合实用性的一些重要问题。最后，我们以当前的研究差距和未来研究的潜在见解得出结论。

Transfer learning aims at improving the performance of target learners on target domains by transferring the knowledge contained in different but related source domains. In this way, the dependence on a large number of target domain data can be reduced for constructing target learners. Due to the wide application prospects, transfer learning has become a popular and promising area in machine learning. Although there are already some valuable and impressive surveys on transfer learning, these surveys introduce approaches in a relatively isolated way and lack the recent advances in transfer learning. Due to the rapid expansion of the transfer learning area, it is both necessary and challenging to comprehensively review the relevant studies. This survey attempts to connect and systematize the existing transfer learning researches, as well as to summarize and interpret the mechanisms and the strategies of transfer learning in a comprehensive way, which may help readers have a better understanding of the current research status and ideas. Unlike previous surveys, this survey paper reviews more than forty representative transfer learning approaches, especially homogeneous transfer learning approaches, from the perspectives of data and model. The applications of transfer learning are also briefly introduced. In order to show the performance of different transfer learning models, over twenty representative transfer learning models are used for experiments. The models are performed on three different datasets, i.e., Amazon Reviews, Reuters-21578, and Office-31. And the experimental results demonstrate the importance of selecting appropriate transfer learning models for different applications in practice.

即使机器学习算法已经在数据科学中发挥了重要作用，但许多当前方法对输入数据提出了不现实的假设。由于不兼容的数据格式，或数据集中的异质，分层或完全缺少的数据片段，因此很难应用此类方法。作为解决方案，我们提出了一个用于样本表示，模型定义和培训的多功能，统一的框架，称为“ Hmill”。我们深入审查框架构建和扩展的机器学习的多个范围范式。从理论上讲，为HMILL的关键组件的设计合理，我们将通用近似定理的扩展显示到框架中实现的模型所实现的所有功能的集合。本文还包含有关我们实施中技术和绩效改进的详细讨论，该讨论将在MIT许可下发布供下载。该框架的主要资产是其灵活性，它可以通过相同的工具对不同的现实世界数据源进行建模。除了单独观察到每个对象的一组属性的标准设置外，我们解释了如何在框架中实现表示整个对象系统的图表中的消息推断。为了支持我们的主张，我们使用框架解决了网络安全域的三个不同问题。第一种用例涉及来自原始网络观察结果的IoT设备识别。在第二个问题中，我们研究了如何使用以有向图表示的操作系统的快照可以对恶意二进制文件进行分类。最后提供的示例是通过网络中实体之间建模域黑名单扩展的任务。在所有三个问题中，基于建议的框架的解决方案可实现与专业方法相当的性能。

合奏学习结合了几个单独的模型，以获得更好的概括性能。目前，与浅层或传统模型相比，深度学习体系结构表现更好。深度合奏学习模型结合了深度学习模型以及整体学习的优势，使最终模型具有更好的概括性能。本文回顾了最先进的深度合奏模型，因此是研究人员的广泛摘要。合奏模型广泛地分类为包装，增强，堆叠，基于负相关的深度合奏模型，显式/隐式合奏，同质/异质合奏，基于决策融合策略的深层集合模型。还简要讨论了在不同领域中深层集成模型的应用。最后，我们以一些潜在的未来研究方向结束了本文。

Recent progress in artificial intelligence (AI) has renewed interest in building systems that learn and think like people. Many advances have come from using deep neural networks trained end-to-end in tasks such as object recognition, video games, and board games, achieving performance that equals or even beats humans in some respects. Despite their biological inspiration and performance achievements, these systems differ from human intelligence in crucial ways. We review progress in cognitive science suggesting that truly human-like learning and thinking machines will have to reach beyond current engineering trends in both what they learn, and how they learn it. Specifically, we argue that these machines should (a) build causal models of the world that support explanation and understanding, rather than merely solving pattern recognition problems; (b) ground learning in intuitive theories of physics and psychology, to support and enrich the knowledge that is learned; and (c) harness compositionality and learning-to-learn to rapidly acquire and generalize knowledge to new tasks and situations. We suggest concrete challenges and promising routes towards these goals that can combine the strengths of recent neural network advances with more structured cognitive models.

背景信息：在过去几年中，机器学习（ML）一直是许多创新的核心。然而，包括在所谓的“安全关键”系统中，例如汽车或航空的系统已经被证明是非常具有挑战性的，因为ML的范式转变为ML带来完全改变传统认证方法。目的：本文旨在阐明与ML为基础的安全关键系统认证有关的挑战，以及文献中提出的解决方案，以解决它们，回答问题的问题如何证明基于机器学习的安全关键系统？'方法：我们开展2015年至2020年至2020年之间发布的研究论文的系统文献综述（SLR），涵盖了与ML系统认证有关的主题。总共确定了217篇论文涵盖了主题，被认为是ML认证的主要支柱：鲁棒性，不确定性，解释性，验证，安全强化学习和直接认证。我们分析了每个子场的主要趋势和问题，并提取了提取的论文的总结。结果：单反结果突出了社区对该主题的热情，以及在数据集和模型类型方面缺乏多样性。它还强调需要进一步发展学术界和行业之间的联系，以加深域名研究。最后，它还说明了必须在上面提到的主要支柱之间建立连接的必要性，这些主要柱主要主要研究。结论：我们强调了目前部署的努力，以实现ML基于ML的软件系统，并讨论了一些未来的研究方向。

Learning curves provide insight into the dependence of a learner's generalization performance on the training set size. This important tool can be used for model selection, to predict the effect of more training data, and to reduce the computational complexity of model training and hyperparameter tuning. This review recounts the origins of the term, provides a formal definition of the learning curve, and briefly covers basics such as its estimation. Our main contribution is a comprehensive overview of the literature regarding the shape of learning curves. We discuss empirical and theoretical evidence that supports well-behaved curves that often have the shape of a power law or an exponential. We consider the learning curves of Gaussian processes, the complex shapes they can display, and the factors influencing them. We draw specific attention to examples of learning curves that are ill-behaved, showing worse learning performance with more training data. To wrap up, we point out various open problems that warrant deeper empirical and theoretical investigation. All in all, our review underscores that learning curves are surprisingly diverse and no universal model can be identified.

自成立以来，选择建模领域一直由理论驱动的建模方法主导。机器学习提供了一种用于建模行为的替代数据驱动方法，越来越越来越欣赏我们的领域。机器学习模型的交叉授粉，技术和实践有助于克服当前理论驱动的建模范式中遇到的问题和限制，例如模型选择的主观劳动密集型搜索过程，无法使用文本和图像数据。然而，尽管使用机器学习的进步来改善选择建模实践的潜在好处，但选择建模领域已经犹豫了拥抱机器学习。本讨论文件旨在巩固用于使用机器学习模型，技术和实践的知识，以获得选择建模，并讨论其潜力。因此，我们希望不仅希望在选择建模中进一步集成机器学习的情况是有益的，而且还可以进一步方便。为此，我们澄清了两个建模范式之间的相似性和差异;我们审查了机器学习选择建模;我们探讨了拥抱机器学习模式和技术的机会领域，以改善我们的实践。要结束本讨论文件，我们提出了一系列的研究问题，必须解决，以更好地了解机器学习如何受益选择建模。

我们介绍了数据科学预测生命周期中各个阶段开发和采用自动化的技术和文化挑战的说明概述，从而将重点限制为使用结构化数据集的监督学习。此外，我们回顾了流行的开源Python工具，这些工具实施了针对自动化挑战的通用解决方案模式，并突出了我们认为进步仍然需要的差距。

Concept drift primarily refers to an online supervised learning scenario when the relation between the input data and the target variable changes over time. Assuming a general knowledge of supervised learning in this paper we characterize adaptive learning process, categorize existing strategies for handling concept drift, overview the most representative, distinct and popular techniques and algorithms, discuss evaluation methodology of adaptive algorithms, and present a set of illustrative applications. The survey covers the different facets of concept drift in an integrated way to reflect on the existing scattered state-of-the-art. Thus, it aims at providing a comprehensive introduction to the concept drift adaptation for researchers, industry analysts and practitioners.

异构表格数据是最常用的数据形式，对于众多关键和计算要求的应用程序至关重要。在同质数据集上，深度神经网络反复显示出卓越的性能，因此被广泛采用。但是，它们适应了推理或数据生成任务的表格数据仍然具有挑战性。为了促进该领域的进一步进展，这项工作概述了表格数据的最新深度学习方法。我们将这些方法分为三组：数据转换，专业体系结构和正则化模型。对于每个小组，我们的工作提供了主要方法的全面概述。此外，我们讨论了生成表格数据的深度学习方法，并且还提供了有关解释对表格数据的深层模型的策略的概述。因此，我们的第一个贡献是解决上述领域中的主要研究流和现有方法，同时强调相关的挑战和开放研究问题。我们的第二个贡献是在传统的机器学习方法中提供经验比较，并在五个流行的现实世界中的十种深度学习方法中，具有不同规模和不同的学习目标的经验比较。我们已将作为竞争性基准公开提供的结果表明，基于梯度增强的树合奏的算法仍然大多在监督学习任务上超过了深度学习模型，这表明对表格数据的竞争性深度学习模型的研究进度停滞不前。据我们所知，这是对表格数据深度学习方法的第一个深入概述。因此，这项工作可以成为有价值的起点，以指导对使用表格数据深入学习感兴趣的研究人员和从业人员。

This paper surveys the recent attempts, both from the machine learning and operations research communities, at leveraging machine learning to solve combinatorial optimization problems. Given the hard nature of these problems, state-of-the-art algorithms rely on handcrafted heuristics for making decisions that are otherwise too expensive to compute or mathematically not well defined. Thus, machine learning looks like a natural candidate to make such decisions in a more principled and optimized way. We advocate for pushing further the integration of machine learning and combinatorial optimization and detail a methodology to do so. A main point of the paper is seeing generic optimization problems as data points and inquiring what is the relevant distribution of problems to use for learning on a given task.

一个令人着迷的假设是，人类和动物的智力可以通过一些原则（而不是启发式方法的百科全书清单）来解释。如果这个假设是正确的，我们可以更容易地理解自己的智能并建造智能机器。就像物理学一样，原理本身不足以预测大脑等复杂系统的行为，并且可能需要大量计算来模拟人类式的智力。这一假设将表明，研究人类和动物所剥削的归纳偏见可以帮助阐明这些原则，并为AI研究和神经科学理论提供灵感。深度学习已经利用了几种关键的归纳偏见，这项工作考虑了更大的清单，重点是关注高级和顺序有意识的处理的工作。阐明这些特定原则的目的是，它们有可能帮助我们建立从人类的能力中受益于灵活分布和系统概括的能力的AI系统，目前，这是一个领域艺术机器学习和人类智力。

The notion of uncertainty is of major importance in machine learning and constitutes a key element of machine learning methodology. In line with the statistical tradition, uncertainty has long been perceived as almost synonymous with standard probability and probabilistic predictions. Yet, due to the steadily increasing relevance of machine learning for practical applications and related issues such as safety requirements, new problems and challenges have recently been identified by machine learning scholars, and these problems may call for new methodological developments. In particular, this includes the importance of distinguishing between (at least) two different types of uncertainty, often referred to as aleatoric and epistemic. In this paper, we provide an introduction to the topic of uncertainty in machine learning as well as an overview of attempts so far at handling uncertainty in general and formalizing this distinction in particular.

所有著名的机器学习算法构成了受监督和半监督的学习工作，只有在一个共同的假设下：培训和测试数据遵循相同的分布。当分布变化时，大多数统计模型必须从新收集的数据中重建，对于某些应用程序，这些数据可能是昂贵或无法获得的。因此，有必要开发方法，以减少在相关领域中可用的数据并在相似领域中进一步使用这些数据，从而减少需求和努力获得新的标签样品。这引起了一个新的机器学习框架，称为转移学习：一种受人类在跨任务中推断知识以更有效学习的知识能力的学习环境。尽管有大量不同的转移学习方案，但本调查的主要目的是在特定的，可以说是最受欢迎的转移学习中最受欢迎的次级领域，概述最先进的理论结果，称为域适应。在此子场中，假定数据分布在整个培训和测试数据中发生变化，而学习任务保持不变。我们提供了与域适应性问题有关的现有结果的首次最新描述，该结果涵盖了基于不同统计学习框架的学习界限。