Binary classification (BC) is a practical task that is ubiquitous in real-world problems, such as distinguishing healthy and unhealthy objects in biomedical diagnostics and defective and non-defective products in manufacturing inspections. Nonetheless, fully annotated data are commonly required to effectively solve this problem, and their collection by domain experts is a tedious and expensive procedure. In contrast to BC, several significant semi-supervised learning techniques that heavily rely on stochastic data augmentation techniques have been devised for solving multi-class classification. In this study, we demonstrate that the stochastic data augmentation technique is less suitable for solving typical BC problems because it can omit crucial features that strictly distinguish between positive and negative samples. To address this issue, we propose a new learning representation to solve the BC problem using a few labels with a random k-pair cross-distance learning mechanism. First, by harnessing a few labeled samples, the encoder network learns the projection of positive and negative samples in angular spaces to maximize and minimize their inter-class and intra-class distances, respectively. Second, the classifier learns to discriminate between positive and negative samples using on-the-fly labels generated based on the angular space and labeled samples to solve BC tasks. Extensive experiments were conducted using four real-world publicly available BC datasets. With few labels and without any data augmentation techniques, the proposed method outperformed state-of-the-art semi-supervised and self-supervised learning methods. Moreover, with 10% labeling, our semi-supervised classifier could obtain competitive accuracy compared with a fully supervised setting.

With the emergence of deep learning, metric learning has gained significant popularity in numerous machine learning tasks dealing with complex and large-scale datasets, such as information retrieval, object recognition and recommendation systems. Metric learning aims to maximize and minimize inter- and intra-class similarities. However, existing models mainly rely on distance measures to obtain a separable embedding space and implicitly maximize the intra-class similarity while neglecting the inter-class relationship. We argue that to enable metric learning as a service for high-performance deep learning applications, we should also wisely deal with inter-class relationships to obtain a more advanced and meaningful embedding space representation. In this paper, a novel metric learning is presented as a service methodology that incorporates covariance to signify the direction of the linear relationship between data points in an embedding space. Unlike conventional metric learning, our covariance-embedding-enhanced approach enables metric learning as a service to be more expressive for computing similar or dissimilar measures and can capture positive, negative, or neutral relationships. Extensive experiments conducted using various benchmark datasets, including natural, biomedical, and facial images, demonstrate that the proposed model as a service with covariance-embedding optimizations can obtain higher-quality, more separable, and more expressive embedding representations than existing models.

我们提出了Parse，这是一种新颖的半监督结构，用于学习强大的脑电图表现以进行情感识别。为了减少大量未标记数据与标记数据有限的潜在分布不匹配，Parse使用成对表示对准。首先，我们的模型执行数据增强，然后标签猜测大量原始和增强的未标记数据。然后将其锐化的标签和标记数据的凸组合锐化。最后，进行表示对准和情感分类。为了严格测试我们的模型，我们将解析与我们实施并适应脑电图学习的几种最先进的半监督方法进行了比较。我们对四个基于公共EEG的情绪识别数据集，种子，种子IV，种子V和Amigos（价和唤醒）进行这些实验。该实验表明，我们提出的框架在种子，种子-IV和Amigos（Valence）中的标记样品有限的情况下，取得了总体最佳效果，同时接近种子V和Amigos中的总体最佳结果（达到第二好） （唤醒）。分析表明，我们的成对表示对齐方式通过减少未标记数据和标记数据之间的分布比对来大大提高性能，尤其是当每类仅1个样本被标记时。

Deep metric learning (DML) aims to automatically construct task-specific distances or similarities of data, resulting in a low-dimensional representation. Several significant metric-learning methods have been proposed. Nonetheless, no approach guarantees the preservation of the ordinal nature of the original data in a low-dimensional space. Ordinal data are ubiquitous in real-world problems, such as the severity of symptoms in biomedical cases, production quality in manufacturing, rating level in businesses, and aging level in face recognition. This study proposes a novel angular triangle distance (ATD) and ordinal triplet network (OTD) to obtain an accurate and meaningful embedding space representation for ordinal data. The ATD projects the ordinal relation of data in the angular space, whereas the OTD learns its ordinal projection. We also demonstrated that our new distance measure satisfies the distance metric properties mathematically. The proposed method was assessed using real-world data with an ordinal nature, such as biomedical, facial, and hand-gestured images. Extensive experiments have been conducted, and the results show that our proposed method not only semantically preserves the ordinal nature but is also more accurate than existing DML models. Moreover, we also demonstrate that our proposed method outperforms the state-of-the-art ordinal metric learning method.

我们提出了一个新颖的半监督学习框架，该框架巧妙地利用了模型的预测，从两个强烈的图像观点中的预测之间的一致性正则化，并由伪标签的信心加权，称为conmatch。虽然最新的半监督学习方法使用图像的弱和强烈的观点来定义方向的一致性损失，但如何为两个强大的观点之间的一致性定义定义这种方向仍然没有探索。为了解决这个问题，我们通过弱小的观点作为非参数和参数方法中的锚点来提出从强大的观点中对伪标签的新颖置信度度量。特别是，在参数方法中，我们首次介绍了伪标签在网络中的信心，该网络的信心是以端到端方式通过骨干模型学习的。此外，我们还提出了阶段训练，以提高培训的融合。当纳入现有的半监督学习者中时，并始终提高表现。我们进行实验，以证明我们对最新方法的有效性并提供广泛的消融研究。代码已在https://github.com/jiwoncocoder/conmatch上公开提供。

长期以来，半监督学习（SSL）已被证明是一种有限的标签模型的有效技术。在现有的文献中，基于一致性的基于正则化的方法，这些方法迫使扰动样本具有类似的预测，而原始的样本则引起了极大的关注。但是，我们观察到，当标签变得极为有限时，例如，每个类别的2或3标签时，此类方法的性能会大大降低。我们的实证研究发现，主要问题在于语义信息在数据增强过程中的漂移。当提供足够的监督时，可以缓解问题。但是，如果几乎没有指导，错误的正则化将误导网络并破坏算法的性能。为了解决该问题，我们（1）提出了一种基于插值的方法来构建更可靠的正样品对； （2）设计一种新颖的对比损失，以指导学习网络的嵌入以在样品之间进行线性更改，从而通过扩大保证金决策边界来提高网络的歧视能力。由于未引入破坏性正则化，因此我们提出的算法的性能在很大程度上得到了改善。具体而言，所提出的算法的表现优于第二好算法（COMATT），而当CIFAR-10数据集中的每个类只有两个标签可用时，可以实现88.73％的分类精度，占5.3％。此外，我们通过通过我们提出的策略大大改善现有最新算法的性能，进一步证明了所提出的方法的普遍性。

组织病理学图像包含丰富的表型信息和病理模式，这是疾病诊断的黄金标准，对于预测患者预后和治疗结果至关重要。近年来，在临床实践中迫切需要针对组织病理学图像的计算机自动化分析技术，而卷积神经网络代表的深度学习方法已逐渐成为数字病理领域的主流。但是，在该领域获得大量细粒的注释数据是一项非常昂贵且艰巨的任务，这阻碍了基于大量注释数据的传统监督算法的进一步开发。最新的研究开始从传统的监督范式中解放出来，最有代表性的研究是基于弱注释，基于有限的注释的半监督学习范式以及基于自我监督的学习范式的弱监督学习范式的研究图像表示学习。这些新方法引发了针对注释效率的新自动病理图像诊断和分析。通过对130篇论文的调查，我们对从技术和方法论的角度来看，对计算病理学领域中有关弱监督学习，半监督学习以及自我监督学习的最新研究进行了全面的系统综述。最后，我们提出了这些技术的关键挑战和未来趋势。

Jitendra Malik once said, "Supervision is the opium of the AI researcher". Most deep learning techniques heavily rely on extreme amounts of human labels to work effectively. In today's world, the rate of data creation greatly surpasses the rate of data annotation. Full reliance on human annotations is just a temporary means to solve current closed problems in AI. In reality, only a tiny fraction of data is annotated. Annotation Efficient Learning (AEL) is a study of algorithms to train models effectively with fewer annotations. To thrive in AEL environments, we need deep learning techniques that rely less on manual annotations (e.g., image, bounding-box, and per-pixel labels), but learn useful information from unlabeled data. In this thesis, we explore five different techniques for handling AEL.

监管基于深度学习的方法，产生医学图像分割的准确结果。但是，它们需要大量标记的数据集，并获得它们是一种艰苦的任务，需要临床专业知识。基于半/自我监督的学习方法通​​过利用未标记的数据以及有限的注释数据来解决此限制。最近的自我监督学习方法使用对比损失来从未标记的图像中学习良好的全球层面表示，并在像想象网那样的流行自然图像数据集上实现高性能。在诸如分段的像素级预测任务中，对于学习良好的本地级别表示以及全局表示来说至关重要，以实现更好的准确性。然而，现有的局部对比损失的方法的影响仍然是学习良好本地表现的限制，因为类似于随机增强和空间接近定义了类似和不同的局部区域;由于半/自我监督设置缺乏大规模专家注释，而不是基于当地地区的语义标签。在本文中，我们提出了局部对比损失，以便通过利用从未标记的图像的未标记图像的伪标签获得的语义标签信息来学习用于分割的良好像素级别特征。特别地，我们定义了建议的损失，以鼓励具有相同伪标签/标签的像素的类似表示，同时与数据集中的不同伪标签/标签的像素的表示。我们通过联合优化标记和未标记的集合和仅限于标记集的分割损失，通过联合优化拟议的对比损失来进行基于伪标签的自培训和培训网络。我们在三个公共心脏和前列腺数据集上进行了评估，并获得高分割性能。

深度学习已成为火星探索的强大工具。火星地形细分是一项重要的火星愿景任务，它是漫游者自动计划和安全驾驶的基础。但是，现有的基于深度学习的地形细分方法遇到了两个问题：一个是缺乏足够的详细和高信心注释，另一个是模型过度依赖于注释的培训数据。在本文中，我们从联合数据和方法设计的角度解决了这两个问题。我们首先提出了一个新的火星地形细分数据集，该数据集包含6K高分辨率图像，并根据置信度稀疏注释，以确保标签的高质量。然后从这些稀疏的数据中学习，我们为火星地形细分的基于表示的学习框架，包括一个自我监督的学习阶段（用于预训练）和半监督的学习阶段（用于微调）。具体而言，对于自我监督的学习，我们设计了一个基于掩盖图像建模（MIM）概念的多任务机制，以强调图像的纹理信息。对于半监督的学习，由于我们的数据集很少注释，因此我们鼓励该模型通过在线生成和利用伪标签来挖掘每个图像中未标记的区域的信息。我们将数据集和方法命名为MARS（S $^{5} $ MARS）的自我监督和半监督分割。实验结果表明，我们的方法可以超越最先进的方法，并通过很大的边距提高地形分割性能。

在新颖的类发现（NCD）中，目标是在一个未标记的集合中找到新的类，并给定一组已知但不同的类别。尽管NCD最近引起了社区的关注，但尽管非常普遍的数据表示，但尚未提出异质表格数据的框架。在本文中，我们提出了TabularNCD，这是一种在表格数据中发现新类别的新方法。我们展示了一种从已知类别中提取知识的方法，以指导包含异质变量的表格数据中新型类的发现过程。该过程的一部分是通过定义伪标签的新方法来完成的，我们遵循多任务学习中的最新发现以优化关节目标函数。我们的方法表明，NCD不仅适用于图像，而且适用于异质表格数据。进行了广泛的实验，以评估我们的方法并证明其对7种不同公共分类数据集的3个竞争对手的有效性。

从积极和未标记的（PU）数据中学习是一种设置，学习者只能访问正面和未标记的样本，而没有关于负面示例的信息。这种PU环境在各种任务中非常重要，例如医学诊断，社交网络分析，金融市场分析和知识基础完成，这些任务也往往本质上是不平衡的，即大多数示例实际上是负面的。但是，大多数现有的PU学习方法仅考虑人工平衡的数据集，目前尚不清楚它们在不平衡和长尾数据分布的现实情况下的表现如何。本文提议通过强大而有效的自我监督预处理来应对这一挑战。但是，培训传统的自我监督学习方法使用高度不平衡的PU分布需要更好的重新重新制定。在本文中，我们提出\ textit {Impulses}，这是\ usewanced {im}平衡\下划线{p} osive \ unesive \ usepline {u} nlabeLed \ underline {l}的统一表示的学习框架{p}。 \下划线{s}削弱了debiase预训练。 Impulses使用大规模无监督学习的通用组合以及对比度损失和额外重新持续的PU损失的一般组合。我们在多个数据集上进行了不同的实验，以表明Impuls能够使先前最新的错误率减半，即使与先前给出的真实先验的方法相比。此外，即使在无关的数据集上进行了预处理，我们的方法也表现出对事先错误指定和卓越性能的鲁棒性。我们预计，这种稳健性和效率将使从业者更容易在其他感兴趣的PU数据集上获得出色的结果。源代码可在\ url {https://github.com/jschweisthal/impulses}中获得

学习时间序列表示只有未标记的数据或几个标签样本可用时，可能是一项具有挑战性的任务。最近，通过对比，通过对比的不同数据观点从未标记的数据中提取有用的表示形式方面，对对比的自我监督学习表现出了很大的改进。在这项工作中，我们通过时间和上下文对比（TS-TCC）提出了一个新颖的时间序列表示学习框架，该框架从未标记的数据中学习了具有对比性学习的无标记数据的表示。具体而言，我们建议时间序列特定的弱和强大的增强，并利用他们的观点在拟议的时间对比模块中学习稳健的时间关系，除了通过我们提出的上下文对比模块学习判别性表示。此外，我们对时间序列数据增强选择进行系统研究，这是对比度学习的关键部分。我们还将TS-TCC扩展到了半监督的学习设置，并提出了一种类感知的TS-TCC（CA-TCC），从可用的少数标​​记数据中受益，以进一步改善TS-TCC学到的表示。具体而言，我们利用TS-TCC生成的强大伪标签来实现班级感知的对比损失。广泛的实验表明，对我们提议的框架所学的功能的线性评估与完全监督的培训相当。此外，我们的框架在少数标记的数据和转移学习方案中显示出高效率。该代码可在\ url {https://github.com/emadeldeen24/ts-tcc}上公开获得。

在对比学习中，最近的进步表现出了出色的表现。但是，绝大多数方法仅限于封闭世界的环境。在本文中，我们通过挖掘开放世界的环境来丰富表示学习的景观，其中新颖阶级的未标记样本自然可以在野外出现。为了弥合差距，我们引入了一个新的学习框架，开放世界的对比学习（Opencon）。Opencon应对已知和新颖阶级学习紧凑的表现的挑战，并促进了一路上的新颖性发现。我们证明了Opencon在挑战基准数据集中的有效性并建立竞争性能。在Imagenet数据集上，Opencon在新颖和总体分类精度上分别胜过当前最佳方法的最佳方法，分别胜过11.9％和7.4％。我们希望我们的工作能为未来的工作打开新的大门，以解决这一重要问题。

培训深层神经网络以识别图像识别通常需要大规模的人类注释数据。为了减少深神经溶液对标记数据的依赖，文献中已经提出了最先进的半监督方法。尽管如此，在面部表达识别领域（FER）领域，使用这种半监督方法非常罕见。在本文中，我们介绍了一项关于最近提出的在FER背景下的最先进的半监督学习方法的全面研究。我们对八种半监督学习方法进行了比较研究当使用各种标记的样品时。我们还将这些方法的性能与完全监督的培训进行了比较。我们的研究表明，当培训现有的半监督方法时，每类标记的样本只有250个标记的样品可以产生可比的性能，而在完整标记的数据集中训练的完全监督的方法。为了促进该领域的进一步研究，我们在：https：//github.com/shuvenduroy/ssl_fer上公开提供代码

This work tackles the problem of semi-supervised learning of image classifiers. Our main insight is that the field of semi-supervised learning can benefit from the quickly advancing field of self-supervised visual representation learning. Unifying these two approaches, we propose the framework of self-supervised semi-supervised learning (S 4 L) and use it to derive two novel semi-supervised image classification methods. We demonstrate the effectiveness of these methods in comparison to both carefully tuned baselines, and existing semi-supervised learning methods. We then show that S 4 L and existing semi-supervised methods can be jointly trained, yielding a new state-of-the-art result on semi-supervised ILSVRC-2012 with 10% of labels.

我们对最近的自我和半监督ML技术进行严格的评估，从而利用未标记的数据来改善下游任务绩效，以河床分割的三个遥感任务，陆地覆盖映射和洪水映射。这些方法对于遥感任务特别有价值，因为易于访问未标记的图像，并获得地面真理标签通常可以昂贵。当未标记的图像（标记数据集之外）提供培训时，我们量化性能改进可以对这些遥感分割任务进行期望。我们还设计实验以测试这些技术的有效性，当测试集相对于训练和验证集具有域移位时。

Semi-supervised anomaly detection is a common problem, as often the datasets containing anomalies are partially labeled. We propose a canonical framework: Semi-supervised Pseudo-labeler Anomaly Detection with Ensembling (SPADE) that isn't limited by the assumption that labeled and unlabeled data come from the same distribution. Indeed, the assumption is often violated in many applications - for example, the labeled data may contain only anomalies unlike unlabeled data, or unlabeled data may contain different types of anomalies, or labeled data may contain only 'easy-to-label' samples. SPADE utilizes an ensemble of one class classifiers as the pseudo-labeler to improve the robustness of pseudo-labeling with distribution mismatch. Partial matching is proposed to automatically select the critical hyper-parameters for pseudo-labeling without validation data, which is crucial with limited labeled data. SPADE shows state-of-the-art semi-supervised anomaly detection performance across a wide range of scenarios with distribution mismatch in both tabular and image domains. In some common real-world settings such as model facing new types of unlabeled anomalies, SPADE outperforms the state-of-the-art alternatives by 5% AUC in average.

Semi-supervised learning (SSL) has achieved great success in leveraging a large amount of unlabeled data to learn a promising classifier. A popular approach is pseudo-labeling that generates pseudo labels only for those unlabeled data with high-confidence predictions. As for the low-confidence ones, existing methods often simply discard them because these unreliable pseudo labels may mislead the model. Nevertheless, we highlight that these data with low-confidence pseudo labels can be still beneficial to the training process. Specifically, although the class with the highest probability in the prediction is unreliable, we can assume that this sample is very unlikely to belong to the classes with the lowest probabilities. In this way, these data can be also very informative if we can effectively exploit these complementary labels, i.e., the classes that a sample does not belong to. Inspired by this, we propose a novel Contrastive Complementary Labeling (CCL) method that constructs a large number of reliable negative pairs based on the complementary labels and adopts contrastive learning to make use of all the unlabeled data. Extensive experiments demonstrate that CCL significantly improves the performance on top of existing methods. More critically, our CCL is particularly effective under the label-scarce settings. For example, we yield an improvement of 2.43% over FixMatch on CIFAR-10 only with 40 labeled data.

Despite significant advances, the performance of state-of-the-art continual learning approaches hinges on the unrealistic scenario of fully labeled data. In this paper, we tackle this challenge and propose an approach for continual semi-supervised learning -- a setting where not all the data samples are labeled. An underlying issue in this scenario is the model forgetting representations of unlabeled data and overfitting the labeled ones. We leverage the power of nearest-neighbor classifiers to non-linearly partition the feature space and learn a strong representation for the current task, as well as distill relevant information from previous tasks. We perform a thorough experimental evaluation and show that our method outperforms all the existing approaches by large margins, setting a strong state of the art on the continual semi-supervised learning paradigm. For example, on CIFAR100 we surpass several others even when using at least 30 times less supervision (0.8% vs. 25% of annotations).