对比度学习（CL）在任何监督的多级分类或无监督的学习中显示出令人印象深刻的图像表示学习进步。但是，这些CL方法无法直接适应多标签图像分类，因为难以定义正面和负面实例以对比多标签场景中给定的锚图像对比给定的锚图像，让标签单独丢失，这意味着借用了借用的标签通常，从对比度多级学习来定义它们的常用方式将产生许多不利的虚假负面实例。在本文中，通过引入标签校正机制来识别缺失的标签，我们首先优雅地产生了锚映像的单个语义标签的阳性和负面因素，然后定义了带有缺少标签的多标签图像分类的独特对比度损失（CLML） ），损失能够准确地使图像接近其真实的正面图像和虚假的负面图像，远离其真实的负面图像。与现有的多标签CL损失不同，CLML还保留了潜在表示空间中的低排名全球和局部标签依赖关系，在这些空间中，已证明此类依赖性有助于处理缺失的标签。据我们所知，这是在缺失标签方案中的第一个一般多标签CL损失，因此可以通过单个超参数与任何现有多标签学习方法的损失无缝配对。已提出的策略已被证明可以在三个标准数据集（MSCOCO，VOC和NUS范围内）提高RESNET101模型的分类性能，分别为1.2％，1.6％和1.3％。代码可在https://github.com/chuangua/contrastivelossmlml上找到。

元学习在有限的监督数据中表现出了几次学习的巨大成功。在这些设置中，元模型通常被过度参数化。尽管常规的统计学习理论表明，过度参数化的模型倾向于过度合适，但经验证据表明，过度参数化的元学习方法仍然很好地工作 - 这种现象通常称为``良性过度拟合''。我们了解这种现象，我们专注于元学习设置，我们将具有挑战性的嵌套结构称为嵌套的元学习，并在过度参数化的元学习模型下分析其泛化性能。尽管我们的分析使用了相对可牵引的线性模型，但我们的理论有助于理解数据异质性，模型适应和良性过度适应嵌套元学习任务之间的微妙相互作用。我们通过数值模拟证实了我们的理论主张。

模型不合时宜的元学习（MAML）目前是少量元学习的主要方法之一。尽管它具有有效性，但由于先天的二聚体问题结构，MAML的优化可能具有挑战性。具体而言，MAML的损失格局比其经验风险最小化的对应物更为复杂，可能的鞍点和局部最小化可能更复杂。为了应对这一挑战，我们利用了最近发明的清晰度最小化的最小化，并开发出一种清晰感的MAML方法，我们称其为Sharp MAML。我们从经验上证明，Sharp-MAML及其计算有效的变体可以胜过流行的现有MAML基准（例如，Mini-Imagenet上的$+12 \％$ $精度）。我们通过收敛速率分析和尖锐MAML的概括结合进行了经验研究。据我们所知，这是在双层学习背景下对清晰度感知最小化的第一个经验和理论研究。该代码可在https://github.com/mominabbass/sharp-maml上找到。

车辆重新识别（RE-ID）旨在通过不同的摄像机检索具有相同车辆ID的图像。当前的零件级特征学习方法通​​常通过统一的部门，外部工具或注意力建模来检测车辆零件。但是，此部分功能通常需要昂贵的额外注释，并在不可靠的零件遮罩预测的情况下导致次优性能。在本文中，我们提出了一个针对车辆重新ID的弱监督零件注意网络（Panet）和零件式网络（PMNET）。首先，Panet通过与零件相关的通道重新校准和基于群集的掩模生成无需车辆零件监管信息来定位车辆零件。其次，PMNET利用教师指导的学习来从锅et中提取特定于车辆的特定功能，并进行多尺度的全球零件特征提取。在推断过程中，PMNET可以自适应提取歧视零件特征，而无需围绕锅et定位，从而防止了不稳定的零件掩模预测。我们将重新ID问题作为一个多任务问题，并采用同质的不确定性来学习最佳的ID损失权衡。实验是在两个公共基准上进行的，这表明我们的方法优于最近的方法，这不需要额外的注释，即CMC@5的平均增加3.0％，而Veri776的MAP中不需要超过1.4％。此外，我们的方法可以扩展到遮挡的车辆重新ID任务，并具有良好的概括能力。

Performance of machine learning algorithms depends critically on identifying a good set of hyperparameters. While recent approaches use Bayesian optimization to adaptively select configurations, we focus on speeding up random search through adaptive resource allocation and early-stopping. We formulate hyperparameter optimization as a pure-exploration nonstochastic infinite-armed bandit problem where a predefined resource like iterations, data samples, or features is allocated to randomly sampled configurations. We introduce a novel algorithm, Hyperband, for this framework and analyze its theoretical properties, providing several desirable guarantees. Furthermore, we compare Hyperband with popular Bayesian optimization methods on a suite of hyperparameter optimization problems. We observe that Hyperband can provide over an order-of-magnitude speedup over our competitor set on a variety of deep-learning and kernel-based learning problems.

Deep learning models can achieve high accuracy when trained on large amounts of labeled data. However, real-world scenarios often involve several challenges: Training data may become available in installments, may originate from multiple different domains, and may not contain labels for training. Certain settings, for instance medical applications, often involve further restrictions that prohibit retention of previously seen data due to privacy regulations. In this work, to address such challenges, we study unsupervised segmentation in continual learning scenarios that involve domain shift. To that end, we introduce GarDA (Generative Appearance Replay for continual Domain Adaptation), a generative-replay based approach that can adapt a segmentation model sequentially to new domains with unlabeled data. In contrast to single-step unsupervised domain adaptation (UDA), continual adaptation to a sequence of domains enables leveraging and consolidation of information from multiple domains. Unlike previous approaches in incremental UDA, our method does not require access to previously seen data, making it applicable in many practical scenarios. We evaluate GarDA on two datasets with different organs and modalities, where it substantially outperforms existing techniques.

The development of social media user stance detection and bot detection methods rely heavily on large-scale and high-quality benchmarks. However, in addition to low annotation quality, existing benchmarks generally have incomplete user relationships, suppressing graph-based account detection research. To address these issues, we propose a Multi-Relational Graph-Based Twitter Account Detection Benchmark (MGTAB), the first standardized graph-based benchmark for account detection. To our knowledge, MGTAB was built based on the largest original data in the field, with over 1.55 million users and 130 million tweets. MGTAB contains 10,199 expert-annotated users and 7 types of relationships, ensuring high-quality annotation and diversified relations. In MGTAB, we extracted the 20 user property features with the greatest information gain and user tweet features as the user features. In addition, we performed a thorough evaluation of MGTAB and other public datasets. Our experiments found that graph-based approaches are generally more effective than feature-based approaches and perform better when introducing multiple relations. By analyzing experiment results, we identify effective approaches for account detection and provide potential future research directions in this field. Our benchmark and standardized evaluation procedures are freely available at: https://github.com/GraphDetec/MGTAB.

As one of the prevalent methods to achieve automation systems, Imitation Learning (IL) presents a promising performance in a wide range of domains. However, despite the considerable improvement in policy performance, the corresponding research on the explainability of IL models is still limited. Inspired by the recent approaches in explainable artificial intelligence methods, we proposed a model-agnostic explaining framework for IL models called R2RISE. R2RISE aims to explain the overall policy performance with respect to the frames in demonstrations. It iteratively retrains the black-box IL model from the randomized masked demonstrations and uses the conventional evaluation outcome environment returns as the coefficient to build an importance map. We also conducted experiments to investigate three major questions concerning frames' importance equality, the effectiveness of the importance map, and connections between importance maps from different IL models. The result shows that R2RISE successfully distinguishes important frames from the demonstrations.

Compressed videos often exhibit visually annoying artifacts, known as Perceivable Encoding Artifacts (PEAs), which dramatically degrade video visual quality. Subjective and objective measures capable of identifying and quantifying various types of PEAs are critical in improving visual quality. In this paper, we investigate the influence of four spatial PEAs (i.e. blurring, blocking, bleeding, and ringing) and two temporal PEAs (i.e. flickering and floating) on video quality. For spatial artifacts, we propose a visual saliency model with a low computational cost and higher consistency with human visual perception. In terms of temporal artifacts, self-attention based TimeSFormer is improved to detect temporal artifacts. Based on the six types of PEAs, a quality metric called Saliency-Aware Spatio-Temporal Artifacts Measurement (SSTAM) is proposed. Experimental results demonstrate that the proposed method outperforms state-of-the-art metrics. We believe that SSTAM will be beneficial for optimizing video coding techniques.

We propose a distributionally robust return-risk model for Markov decision processes (MDPs) under risk and reward ambiguity. The proposed model optimizes the weighted average of mean and percentile performances, and it covers the distributionally robust MDPs and the distributionally robust chance-constrained MDPs (both under reward ambiguity) as special cases. By considering that the unknown reward distribution lies in a Wasserstein ambiguity set, we derive the tractable reformulation for our model. In particular, we show that that the return-risk model can also account for risk from uncertain transition kernel when one only seeks deterministic policies, and that a distributionally robust MDP under the percentile criterion can be reformulated as its nominal counterpart at an adjusted risk level. A scalable first-order algorithm is designed to solve large-scale problems, and we demonstrate the advantages of our proposed model and algorithm through numerical experiments.