Graph neural networks (GNNs), as the de-facto model class for representation learning on graphs, are built upon the multi-layer perceptrons (MLP) architecture with additional message passing layers to allow features to flow across nodes. While conventional wisdom largely attributes the success of GNNs to their advanced expressivity for learning desired functions on nodes' ego-graphs, we conjecture that this is \emph{not} the main cause of GNNs' superiority in node prediction tasks. This paper pinpoints the major source of GNNs' performance gain to their intrinsic generalization capabilities, by introducing an intermediate model class dubbed as P(ropagational)MLP, which is identical to standard MLP in training, and then adopt GNN's architecture in testing. Intriguingly, we observe that PMLPs consistently perform on par with (or even exceed) their GNN counterparts across ten benchmarks and different experimental settings, despite the fact that PMLPs share the same (trained) weights with poorly-performed MLP. This critical finding opens a door to a brand new perspective for understanding the power of GNNs, and allow bridging GNNs and MLPs for dissecting their generalization behaviors. As an initial step to analyze PMLP, we show its essential difference with MLP at infinite-width limit lies in the NTK feature map in the post-training stage. Moreover, though MLP and PMLP cannot extrapolate non-linear functions for extreme OOD data, PMLP has more freedom to generalize near the training support.

基于模型的离线优化通过动态感知政策为策略学习和分布外概括提供了新的观点，在该策略中，学会的政策可以适应培训阶段列举的不同动态。但是，由于离线设置下的限制，学到的模型无法很好地模仿真实的动态，以支持可靠的分发勘探，这仍然阻碍了政策以良好的概括。为了缩小差距，先前的作品大致集成了随机初始化的模型，以更好地近似实际动力学。但是，这种做法是昂贵且效率低下的，并且无法保证学识渊博的模型可以近似真正的动态，我们在本文中命名了覆盖性。我们通过生成具有可证明的能力以有效且可控制的方式覆盖真实动态的模型来积极解决这个问题。为此，我们根据动力学下的策略占用，为动态模型设计一个距离度量，并提出了一种算法来生成模型，以优化其对真实动力学的覆盖范围。我们对模型生成过程进行了理论分析，并证明我们的算法可以提供增强的覆盖性。作为一项下游任务，我们以较小或没有保守的惩罚训练动态感知政策，实验表明我们的算法在现有的离线RL基准测试中优于先前的离线方法。我们还发现，通过我们的方法学到的政策具有更好的零转移性能，这意味着它们的概括更好。

PCL检测任务旨在识别和分类语言，这些语言是光顾或屈服于一般媒体中的脆弱社区。 ，使通用文本分类方法的表现令人失望。针对Semeval-2022任务4中的PCL检测问题，在本文中，我们对团队的解决方案进行了介绍，该解决方案利用了基于段落分类的及时学习的力量。我们将任务重新制定为适当的披肩提示，并使用预先训练的蒙版语言模型来填补披肩插槽。对于这两个子任务，即二进制分类和多标签分类，采用并微调Deberta模型来预测特定于任务的提示的标签单词。在评估数据集中，对于二进制分类，我们的方法达到了0.6406的F1分数；对于多标签分类，我们的方法达到了0.4689的宏F1得分，在排行榜中排名第一。

使用无法回答的问题的机器阅读理解是一项艰巨的NLP任务，受到无法从段落回答的问题的挑战。据观察，微妙的文字变化通常使一个可回答的问题无法回答，但是，大多数MRC模型无法识别此类变化。为了解决这个问题，在本文中，我们提出了一种基于跨度的对比度学习方法（SPANCL），该方法在答案跨度上明确将可回答的问题与他们的回答和无法回答的对应物进行了明确的对比。使用SPANCL，MRC模型被迫从微小的字面差异中感知至关重要的语义变化。小队2.0数据集的实验表明，SPANCL可以显着改善基准，从而产生0.86-2.14绝对EM的改进。其他实验还表明，Spancl是利用生成问题的有效方法。

评估当前序列或对话级Chatbots（例如Impathetic Open-Domain对话模型）的一个挑战是确定Chatbot是否以情绪一致的方式执行。最近的工作仅在对话之间的语境一致性，语言流畅性，响应多样性或逻辑自我一致性的方面进行评估。这项工作建议培训评估员以确定聊天禁令的情绪一致性。

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.