在研究积极的学习时，我们专注于标记的示例数量（预算规模）和合适的查询策略之间的关系。我们的理论分析表明，一种让人联想到相变的行为：预算低时最好查询典型的示例，而预算较大时最好查询无代表性的示例。合并的证据表明，类似的现象发生在共同的分类模型中。因此，我们提出了典型lust，这是一种适合低预算的深度积极学习策略。在对监督学习的比较实证研究中，使用各种架构和图像数据集，TypicLust在低预算制度中的所有其他活跃学习策略都优于所有其他活跃的学习策略。在半监督框架中使用TypicLust，性能得到更加显着的提升。特别是，在CIFAR-10上训练的最新半监督方法，由Typiclust选择的10个标记的示例训练，达到93.2％的精度 - 比随机选择提高了39.4％。代码可在https://github.com/avihu111/typiclust上找到。

Deep active learning aims to reduce the annotation cost for the training of deep models, which is notoriously data-hungry. Until recently, deep active learning methods were ineffectual in the low-budget regime, where only a small number of examples are annotated. The situation has been alleviated by recent advances in representation and self-supervised learning, which impart the geometry of the data representation with rich information about the points. Taking advantage of this progress, we study the problem of subset selection for annotation through a "covering" lens, proposing ProbCover - a new active learning algorithm for the low budget regime, which seeks to maximize Probability Coverage. We then describe a dual way to view the proposed formulation, from which one can derive strategies suitable for the high budget regime of active learning, related to existing methods like Coreset. We conclude with extensive experiments, evaluating ProbCover in the low-budget regime. We show that our principled active learning strategy improves the state-of-the-art in the low-budget regime in several image recognition benchmarks. This method is especially beneficial in the semi-supervised setting, allowing state-of-the-art semi-supervised methods to match the performance of fully supervised methods, while using much fewer labels nonetheless. Code is available at https://github.com/avihu111/TypiClust.

It is widely believed that given the same labeling budget, active learning algorithms like uncertainty sampling achieve better predictive performance than passive learning (i.e. uniform sampling), albeit at a higher computational cost. Recent empirical evidence suggests that this added cost might be in vain, as uncertainty sampling can sometimes perform even worse than passive learning. While existing works offer different explanations in the low-dimensional regime, this paper shows that the underlying mechanism is entirely different in high dimensions: we prove for logistic regression that passive learning outperforms uncertainty sampling even for noiseless data and when using the uncertainty of the Bayes optimal classifier. Insights from our proof indicate that this high-dimensional phenomenon is exacerbated when the separation between the classes is small. We corroborate this intuition with experiments on 20 high-dimensional datasets spanning a diverse range of applications, from finance and histology to chemistry and computer vision.

最近的工作表明，不同体系结构的卷积神经网络学会按照相同的顺序对图像进行分类。为了理解这种现象，我们重新审视了过度参数的深度线性网络模型。我们的分析表明，当隐藏层足够宽时，该模型参数的收敛速率沿数据的较大主组件的方向呈指数级数，该方向由由相应的奇异值控制的速率。我们称这种收敛模式主成分偏差（PC偏置）。从经验上讲，我们展示了PC偏差如何简化线性和非线性网络的学习顺序，在学习的早期阶段更为突出。然后，我们将结果与简单性偏见进行比较，表明可以独立看到这两个偏见，并以不同的方式影响学习顺序。最后，我们讨论了PC偏差如何解释早期停止及其与PCA的联系的一些好处，以及为什么深网与随机标签更慢地收敛。

我们研究了用于半监控学习（SSL）的无监督数据选择，其中可以提供大规模的未标记数据集，并且为标签采集预算小额数据子集。现有的SSL方法专注于学习一个有效地集成了来自给定小标记数据和大型未标记数据的信息的模型，而我们专注于选择正确的数据以用于SSL的注释，而无需任何标签或任务信息。直观地，要标记的实例应统称为下游任务的最大多样性和覆盖范围，并且单独具有用于SSL的最大信息传播实用程序。我们以三步数据为中心的SSL方法形式化这些概念，使稳定性和精度的纤维液改善8％的CiFar-10（标记为0.08％）和14％的Imagenet -1k（标记为0.2％）。它也是一种具有各种SSL方法的通用框架，提供一致的性能增益。我们的工作表明，在仔细选择注释数据上花费的小计算带来了大注释效率和模型性能增益，而无需改变学习管道。我们完全无监督的数据选择可以轻松扩展到其他弱监督的学习设置。

主动学习（AL）算法旨在识别注释的最佳数据子集，使得深神经网络（DNN）在此标记子集上培训时可以实现更好的性能。 AL特别有影响的工业规模设置，其中数据标签成本高，从业者使用各种工具来处理，以提高模型性能。最近自我监督预测（SSP）的成功突出了利用丰富的未标记数据促进模型性能的重要性。通过将AL与SSP结合起来，我们可以使用未标记的数据，同时标记和培训特别是信息样本。在这项工作中，我们研究了Imagenet上的AL和SSP的组合。我们发现小型玩具数据集上的性能 - 文献中的典型基准设置 - 由于活动学习者选择的类不平衡样本，而不是想象中的性能。在我们测试的现有基线中，各种小型和大规​​模设置的流行AL算法未能以随机抽样优于差异。为了解决类别不平衡问题，我们提出了平衡选择（基础），这是一种简单，可伸缩的AL算法，通过选择比现有方法更加平衡样本来始终如一地始终采样。我们的代码可用于：https://github.com/zeyademam/active_learning。

标记大量数据很昂贵。主动学习旨在通过要求注释未标记的集合中最有用的数据来解决这个问题。我们提出了一种新颖的活跃学习方法，该方法利用自我监督的借口任务和独特的数据采样器来选择既困难又具有代表性的数据。我们发现，简单的自我监督借口任务（例如旋转预测）的损失与下游任务损失密切相关。在主动学习迭代之前，对未标记的集合进行了借口任务学习者进行培训，并且未标记的数据被分类并通过其借口任务损失分组成批处理。在每个主动的学习迭代中，主要任务模型用于批评要注释的批次中最不确定的数据。我们评估了有关各种图像分类和分割基准测试的方法，并在CIFAR10，CALTECH-101，IMAGENET和CITYSCAPES上实现引人注目的性能。我们进一步表明，我们的方法在不平衡的数据集上表现良好，并且可以有效地解决冷启动问题的解决方案，在这种问题中，主动学习性能受到随机采样的初始标记集的影响。

我们介绍了有监督的对比度积极学习（SCAL），并根据功能相似性（功能IM）和基于主成分分析的基于特征重建误差（FRE）提出有效的活动学习策略，以选择具有不同特征表示的信息性数据示例。我们证明了我们提出的方法可实现最新的准确性，模型校准并减少在图像分类任务上平衡和不平衡数据集的主动学习设置中的采样偏差。我们还评估了模型的鲁棒性，从主动学习环境中不同查询策略得出的分配转移。使用广泛的实验，我们表明我们提出的方法的表现优于高性能密集型方法，从而使平均损坏误差降低了9.9％，在数据集偏移下的预期校准误差降低了7.2％，而AUROC降低了8.9％的AUROC。检测。

While deep learning succeeds in a wide range of tasks, it highly depends on the massive collection of annotated data which is expensive and time-consuming. To lower the cost of data annotation, active learning has been proposed to interactively query an oracle to annotate a small proportion of informative samples in an unlabeled dataset. Inspired by the fact that the samples with higher loss are usually more informative to the model than the samples with lower loss, in this paper we present a novel deep active learning approach that queries the oracle for data annotation when the unlabeled sample is believed to incorporate high loss. The core of our approach is a measurement Temporal Output Discrepancy (TOD) that estimates the sample loss by evaluating the discrepancy of outputs given by models at different optimization steps. Our theoretical investigation shows that TOD lower-bounds the accumulated sample loss thus it can be used to select informative unlabeled samples. On basis of TOD, we further develop an effective unlabeled data sampling strategy as well as an unsupervised learning criterion for active learning. Due to the simplicity of TOD, our methods are efficient, flexible, and task-agnostic. Extensive experimental results demonstrate that our approach achieves superior performances than the state-of-the-art active learning methods on image classification and semantic segmentation tasks. In addition, we show that TOD can be utilized to select the best model of potentially the highest testing accuracy from a pool of candidate models.

大型标记数据集的可用性是深度学习成功的关键组成部分。但是，大型数据集上的标签通常很耗时且昂贵。主动学习是一个研究领域，通过选择最重要的标签样本来解决昂贵的标签问题。基于多样性的采样算法被称为基于表示的主动学习方法的组成部分。在本文中，我们介绍了一种新的基于多样性的初始数据集选择算法，以选择有效学习环境中初始标记的最有用的样本集。自我监督的表示学习用于考虑初始数据集选择算法中样品的多样性。此外，我们提出了一种新型的主动学习查询策略，该策略使用基于多样性的基于一致性的嵌入方式采样。通过考虑基于一致性的嵌入方案中多样性的一致性信息，该方法可以在半监督的学习环境中选择更多信息的样本来标记。比较实验表明，通过利用未标记的数据的多样性，与先前的主动学习方法相比，该提出的方法在CIFAR-10和CALTECH-101数据集上取得了令人信服的结果。

自我监督学习中的最新作品通过依靠对比度学习范式来推动最先进的工作，该范式通过推动正面对或从同一班级中的类似示例来学习表示形式，同时将负面对截然不同。尽管取得了经验的成功，但理论基础是有限的 - 先前的分析假设鉴于同一类标签的正对有条件独立性，但是最近的经验应用使用了密切相关的正对（即同一图像的数据增强）。我们的工作分析了对比度学习，而无需在数据上使用增强图的新概念假设正对的有条件独立性。此图中的边缘连接相同数据的增强，而地面实际类别自然形成了连接的子图。我们提出了在人口增强图上执行光谱分解的损失，并且可以简洁地作为对神经净表示的对比学习目标。最小化此目标会导致在线性探针评估下具有可证明准确性的功能。通过标准的概括范围，在最大程度地减少训练对比度损失时，这些准确性也可以保证。从经验上讲，我们目标所学的功能可以匹配或胜过基准视觉数据集上的几个强基线。总的来说，这项工作为对比度学习提供了首次可证明的分析，在该学习中，线性探针评估的保证可以适用于现实的经验环境。

近年来，已取得了巨大进展，以通过半监督学习（SSL）来纳入未标记的数据来克服效率低下的监督问题。大多数最先进的模型是基于对未标记的数据追求一致的模型预测的想法，该模型被称为输入噪声，这称为一致性正则化。尽管如此，对其成功的原因缺乏理论上的见解。为了弥合理论和实际结果之间的差距，我们在本文中提出了SSL的最坏情况一致性正则化技术。具体而言，我们首先提出了针对SSL的概括，该概括由分别在标记和未标记的训练数据上观察到的经验损失项组成。在这种界限的激励下，我们得出了一个SSL目标，该目标可最大程度地减少原始未标记的样本与其多重增强变体之间最大的不一致性。然后，我们提供了一种简单但有效的算法来解决提出的最小问题，从理论上证明它会收敛到固定点。五个流行基准数据集的实验验证了我们提出的方法的有效性。

The generalisation performance of a convolutional neural networks (CNN) is majorly predisposed by the quantity, quality, and diversity of the training images. All the training data needs to be annotated in-hand before, in many real-world applications data is easy to acquire but expensive and time-consuming to label. The goal of the Active learning for the task is to draw most informative samples from the unlabeled pool which can used for training after annotation. With total different objective, self-supervised learning which have been gaining meteoric popularity by closing the gap in performance with supervised methods on large computer vision benchmarks. self-supervised learning (SSL) these days have shown to produce low-level representations that are invariant to distortions of the input sample and can encode invariance to artificially created distortions, e.g. rotation, solarization, cropping etc. self-supervised learning (SSL) approaches rely on simpler and more scalable frameworks for learning. In this paper, we unify these two families of approaches from the angle of active learning using self-supervised learning mainfold and propose Deep Active Learning using BarlowTwins(DALBT), an active learning method for all the datasets using combination of classifier trained along with self-supervised loss framework of Barlow Twins to a setting where the model can encode the invariance of artificially created distortions, e.g. rotation, solarization, cropping etc.

State-of-the-art results on image recognition tasks are achieved using over-parameterized learning algorithms that (nearly) perfectly fit the training set and are known to fit well even random labels. This tendency to memorize the labels of the training data is not explained by existing theoretical analyses. Memorization of the training data also presents significant privacy risks when the training data contains sensitive personal information and thus it is important to understand whether such memorization is necessary for accurate learning.We provide the first conceptual explanation and a theoretical model for this phenomenon. Specifically, we demonstrate that for natural data distributions memorization of labels is necessary for achieving closeto-optimal generalization error. Crucially, even labels of outliers and noisy labels need to be memorized. The model is motivated and supported by the results of several recent empirical works. In our model, data is sampled from a mixture of subpopulations and our results show that memorization is necessary whenever the distribution of subpopulation frequencies is long-tailed. Image and text data is known to be long-tailed and therefore our results establish a formal link between these empirical phenomena. Our results allow to quantify the cost of limiting memorization in learning and explain the disparate effects that privacy and model compression have on different subgroups.

Partial label learning (PLL) is an important problem that allows each training example to be labeled with a coarse candidate set, which well suits many real-world data annotation scenarios with label ambiguity. Despite the promise, the performance of PLL often lags behind the supervised counterpart. In this work, we bridge the gap by addressing two key research challenges in PLL -- representation learning and label disambiguation -- in one coherent framework. Specifically, our proposed framework PiCO consists of a contrastive learning module along with a novel class prototype-based label disambiguation algorithm. PiCO produces closely aligned representations for examples from the same classes and facilitates label disambiguation. Theoretically, we show that these two components are mutually beneficial, and can be rigorously justified from an expectation-maximization (EM) algorithm perspective. Moreover, we study a challenging yet practical noisy partial label learning setup, where the ground-truth may not be included in the candidate set. To remedy this problem, we present an extension PiCO+ that performs distance-based clean sample selection and learns robust classifiers by a semi-supervised contrastive learning algorithm. Extensive experiments demonstrate that our proposed methods significantly outperform the current state-of-the-art approaches in standard and noisy PLL tasks and even achieve comparable results to fully supervised learning.

主动学习（AL）是一个有希望的ML范式，有可能解析大型未标记数据并有助于降低标记数据可能令人难以置信的域中的注释成本。最近提出的基于神经网络的AL方法使用不同的启发式方法来实现这一目标。在这项研究中，我们证明，在相同的实验环境下，不同类型的AL算法（基于不确定性，基于多样性和委员会）产生了与随机采样基线相比的不一致增长。通过各种实验，控制了随机性来源，我们表明，AL算法实现的性能指标方差可能会导致与先前报道的结果不符的结果。我们还发现，在强烈的正则化下，AL方法在各种实验条件下显示出比随机采样基线的边缘或没有优势。最后，我们以一系列建议进行结论，以了解如何使用新的AL算法评估结果，以确保在实验条件下的变化下结果可再现和健壮。我们共享我们的代码以促进AL评估。我们认为，我们的发现和建议将有助于使用神经网络在AL中进行可重复的研究。我们通过https://github.com/prateekmunjal/torchal开源代码

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。

哪种结构可以使学习者能够从未标记的数据中发现类？传统方法取决于功能空间的相似性和对数据的英勇假设。在本文中，我们在潜在标签换档（LLS）下介绍了无监督的学习，我们可以从多个域中访问未标记的数据，以便标签边缘$ p_d（y）$可以跨域变化，但是类有条件的$ p（\ mathbf） {x} | y）$不。这项工作实例化了识别类别的新原则：将分组分组的元素。对于有限输入空间，我们在LLS和主题建模之间建立了同构：输入对应于单词，域，文档和标签与主题。解决连续数据时，我们证明，当每个标签的支持包含一个可分离区域时，类似于锚词，Oracle访问$ P（d | \ Mathbf {x}）$足以识别$ p_d（y）$和$ p_d（ y | \ mathbf {x}）$ for排列。因此，我们引入了一种实用算法，该算法利用域 - 歧义模型如下：（i）通过域歧视器$ p（d | \ mathbf {x}）推动示例； （ii）通过$ p（d | \ mathbf {x}）$ space中的聚类示例来离散数据； （iii）对离散数据执行非负矩阵分解； （iv）将回收的$ P（y | d）$与鉴别器输出$ p（d | \ mathbf {x}）$结合在一起计算$ p_d（y | x）\; \ forall d $。通过半合成实验，我们表明我们的算法可以利用域信息来改善无监督的分类方法。当功能空间相似性并不表示真实分组时，我们揭示了标准无监督分类方法的故障模式，并从经验上证明我们的方法可以更好地处理这种情况。我们的结果建立了分销转移与主题建模之间的密切联系，为将来的工作开辟了有希望的界限。

基于池的主动学习（AL）通过依次从大型未标记数据池中选择信息的未标记样本并从Oracle/Ontoter中查询标签，从而取得了巨大成功。但是，现有的AL采样策略可能在分布外（OOD）数据方案中无法很好地工作，其中未标记的数据池包含一些不属于目标任务类别的数据示例。在OOD数据情景下实现良好的AL性能是一项具有挑战性的任务，因为Al采样策略与OOD样本检测之间的自然冲突。 Al选择很难由当前基本分类器进行分类的数据（例如，预测类概率具有较高熵的样品），而OOD样品往往具有比分布更均匀的预测类概率（即高熵）（即高熵）（ID ） 数据。在本文中，我们提出了一种采样方案，即用于主动学习的蒙特 - 卡洛帕累托优化（POAL），该方案从未标记的数据库中选择了具有固定批次大小的未标记样品的最佳子集。我们将AL采样任务施加为多目标优化问题，因此我们基于两个冲突的目标利用Pareto优化：（1）正常的AL数据采样方案（例如，最大熵）和（2）作为OOD样本。实验结果表明其对经典机器学习（ML）和深度学习（DL）任务的有效性。

Active learning aims to develop label-efficient algorithms by sampling the most representative queries to be labeled by an oracle. We describe a pool-based semisupervised active learning algorithm that implicitly learns this sampling mechanism in an adversarial manner. Unlike conventional active learning algorithms, our approach is task agnostic, i.e., it does not depend on the performance of the task for which we are trying to acquire labeled data. Our method learns a latent space using a variational autoencoder (VAE) and an adversarial network trained to discriminate between unlabeled and labeled data. The minimax game between the VAE and the adversarial network is played such that while the VAE tries to trick the adversarial network into predicting that all data points are from the labeled pool, the adversarial network learns how to discriminate between dissimilarities in the latent space. We extensively evaluate our method on various image classification and semantic segmentation benchmark datasets and establish a new state of the art on CIFAR10/100, Caltech-256, ImageNet, Cityscapes, and BDD100K. Our results demonstrate that our adversarial approach learns an effective low dimensional latent space in large-scale settings and provides for a computationally efficient sampling method. 1