近几十年来，科学和工程的可用数据数量的重大增长彻底改变了。然而，尽管现在收集和存储数据的空前很容易，但通过补充每个功能的标签来标记数据仍然是具有挑战性的。标签过程需要专家知识或乏味且耗时的说明任务包括用诊断X射线标记X射线，具有蛋白质类型的蛋白质序列，其主题的文本，通过其情感推文或视频通过其类型的视频。在这些和许多其他示例中，由于成本和时间限制，只能手动标记一些功能。我们如何才能最好地将标签信息从少数昂贵的标签功能到大量未标记的标签信息传播？这是半监督学习（SSL）提出的问题。本文概述了基于图的贝叶斯SSL的最新基础发展，这是一种使用功能之间的相似性的标签传播概率框架。 SSL是一个活跃的研究领域，对现有文献的彻底回顾超出了本文的范围。我们的重点将放在我们自己的研究中得出的主题，这些主题说明了对基于图的贝叶斯SSL的统计准确性和计算效率进行严格研究的广泛数学工具和思想。

我们研究了非参数混合模型中的一致性以及回归的密切相关的混合物（也称为混合回归）模型，其中允许回归函数是非参数的，并且假定误差分布是高斯密度的卷积。我们在一般条件下构建统一的一致估计器，同时突出显示了将现有的点一致性结果扩展到均匀结果的几个疼痛点。最终的分析事实并非如此，并且在此过程中开发了几种新颖的技术工具。在混合回归的情况下，我们证明了回归函数的$ l^1 $收敛性，同时允许组件回归函数任意地相交，这带来了其他技术挑战。我们还考虑对一般（即非跨方向）非参数混合物的概括。

尽管图表学习（GRL）取得了重大进展，但要以足够的方式提取和嵌入丰富的拓扑结构和特征信息仍然是一个挑战。大多数现有方法都集中在本地结构上，并且无法完全融合全球拓扑结构。为此，我们提出了一种新颖的结构保留图表学习（SPGRL）方法，以完全捕获图的结构信息。具体而言，为了减少原始图的不确定性和错误信息，我们通过k-nearest邻居方法构建了特征图作为互补视图。该特征图可用于对比节点级别以捕获本地关系。此外，我们通过最大化整个图形和特征嵌入的相互信息（MI）来保留全局拓扑结构信息，从理论上讲，该信息可以简化为交换功能的特征嵌入和原始图以重建本身。广泛的实验表明，我们的方法在半监督节点分类任务上具有相当出色的性能，并且在图形结构或节点特征上噪声扰动下的鲁棒性出色。

及时调整是将预训练模型调整到下游任务的极其有效的工具。但是，基于标准及时的方法主要考虑下游任务的足够数据的情况。目前尚不清楚是否可以将优势传输到几杆式制度，在每个下游任务中只有有限的数据。尽管有些作品证明了在几次弹奏设置下及时调整的潜力，但通过搜索离散提示或使用有限数据调整软提示的主流方法仍然非常具有挑战性。通过广泛的实证研究，我们发现迅速调整和完全微调之间的学习差距仍然存在差距。为了弥合差距，我们提出了一个新的及时调整框架，称为软模板调整（STT）。 STT结合了手册和自动提示，并将下游分类任务视为掩盖语言建模任务。对不同设置的全面评估表明，STT可以在不引入其他参数的情况下缩小微调和基于及时的方法之间的差距。值得注意的是，它甚至可以胜过情感分类任务的时间和资源消耗的微调方法。

培训文本到图像生成模型中的主要挑战之一是需要大量的高质量图像文本对。虽然图像样本通常很容易接近，但相关的文本描述通常需要仔细的人类标题，这是特别的 - 耗时和成本耗费。在本文中，我们提出了第一项工作来培训没有任何文本数据的文本到图像生成模型。我们的方法利用了强大的预训练剪辑模型的良好对齐的多模态语义空间：通过从图像特征生成文本特征，无缝地减轻了文本调节的要求。进行广泛的实验以说明所提出的方法的有效性。我们在标准的文本到图像生成任务中获得最先进的结果。重要的是，拟议的无语模型优于具有完整图像文本对训练的大多数现有型号。此外，我们的方法可以应用于微调预先训练的模型，它可以节省培训文本到图像生成模型的培训时间和成本。我们预先接受的模型在MS-Coco DataSet上获得竞争激烈的结果，在零拍摄的图像集中在MS-Coco DataSet上产生竞争结果，但距离最近提出的大型Dall-E型号的模型大小和培训数据大小约为1％。

Dataset distillation has emerged as a prominent technique to improve data efficiency when training machine learning models. It encapsulates the knowledge from a large dataset into a smaller synthetic dataset. A model trained on this smaller distilled dataset can attain comparable performance to a model trained on the original training dataset. However, the existing dataset distillation techniques mainly aim at achieving the best trade-off between resource usage efficiency and model utility. The security risks stemming from them have not been explored. This study performs the first backdoor attack against the models trained on the data distilled by dataset distillation models in the image domain. Concretely, we inject triggers into the synthetic data during the distillation procedure rather than during the model training stage, where all previous attacks are performed. We propose two types of backdoor attacks, namely NAIVEATTACK and DOORPING. NAIVEATTACK simply adds triggers to the raw data at the initial distillation phase, while DOORPING iteratively updates the triggers during the entire distillation procedure. We conduct extensive evaluations on multiple datasets, architectures, and dataset distillation techniques. Empirical evaluation shows that NAIVEATTACK achieves decent attack success rate (ASR) scores in some cases, while DOORPING reaches higher ASR scores (close to 1.0) in all cases. Furthermore, we conduct a comprehensive ablation study to analyze the factors that may affect the attack performance. Finally, we evaluate multiple defense mechanisms against our backdoor attacks and show that our attacks can practically circumvent these defense mechanisms.

Blind image quality assessment (BIQA) remains challenging due to the diversity of distortion and image content variation, which complicate the distortion patterns crossing different scales and aggravate the difficulty of the regression problem for BIQA. However, existing BIQA methods often fail to consider multi-scale distortion patterns and image content, and little research has been done on learning strategies to make the regression model produce better performance. In this paper, we propose a simple yet effective Progressive Multi-Task Image Quality Assessment (PMT-IQA) model, which contains a multi-scale feature extraction module (MS) and a progressive multi-task learning module (PMT), to help the model learn complex distortion patterns and better optimize the regression issue to align with the law of human learning process from easy to hard. To verify the effectiveness of the proposed PMT-IQA model, we conduct experiments on four widely used public datasets, and the experimental results indicate that the performance of PMT-IQA is superior to the comparison approaches, and both MS and PMT modules improve the model's performance.

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.

Given the increasingly intricate forms of partial differential equations (PDEs) in physics and related fields, computationally solving PDEs without analytic solutions inevitably suffers from the trade-off between accuracy and efficiency. Recent advances in neural operators, a kind of mesh-independent neural-network-based PDE solvers, have suggested the dawn of overcoming this challenge. In this emerging direction, Koopman neural operator (KNO) is a representative demonstration and outperforms other state-of-the-art alternatives in terms of accuracy and efficiency. Here we present KoopmanLab, a self-contained and user-friendly PyTorch module of the Koopman neural operator family for solving partial differential equations. Beyond the original version of KNO, we develop multiple new variants of KNO based on different neural network architectures to improve the general applicability of our module. These variants are validated by mesh-independent and long-term prediction experiments implemented on representative PDEs (e.g., the Navier-Stokes equation and the Bateman-Burgers equation) and ERA5 (i.e., one of the largest high-resolution data sets of global-scale climate fields). These demonstrations suggest the potential of KoopmanLab to be considered in diverse applications of partial differential equations.

A recent study has shown a phenomenon called neural collapse in that the within-class means of features and the classifier weight vectors converge to the vertices of a simplex equiangular tight frame at the terminal phase of training for classification. In this paper, we explore the corresponding structures of the last-layer feature centers and classifiers in semantic segmentation. Based on our empirical and theoretical analysis, we point out that semantic segmentation naturally brings contextual correlation and imbalanced distribution among classes, which breaks the equiangular and maximally separated structure of neural collapse for both feature centers and classifiers. However, such a symmetric structure is beneficial to discrimination for the minor classes. To preserve these advantages, we introduce a regularizer on feature centers to encourage the network to learn features closer to the appealing structure in imbalanced semantic segmentation. Experimental results show that our method can bring significant improvements on both 2D and 3D semantic segmentation benchmarks. Moreover, our method ranks 1st and sets a new record (+6.8% mIoU) on the ScanNet200 test leaderboard. Code will be available at https://github.com/dvlab-research/Imbalanced-Learning.