在结果决策中使用机器学习模型通常会加剧社会不平等,特别是对种族和性别定义的边缘化群体成员产生不同的影响。 ROC曲线(AUC)下的区域被广泛用于评估机器学习中评分功能的性能,但与其他性能指标相比,在算法公平性中进行了研究。由于AUC的成对性质,定义基于AUC的组公平度量是成对依赖性的,并且可能涉及\ emph {group}和\ emph {group} aucs。重要的是,仅考虑一种AUC类别不足以减轻AUC优化的不公平性。在本文中,我们提出了一个最小值学习和偏置缓解框架,该框架既包含组内和组间AUC,同时保持实用性。基于这个Rawlsian框架,我们设计了一种有效的随机优化算法,并证明了其收敛到最小组级AUC。我们对合成数据集和现实数据集进行了数值实验,以验证Minimax框架的有效性和所提出的优化算法。
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随机梯度下降(SGDA)及其变体一直是解决最小值问题的主力。但是,与研究有差异隐私(DP)约束的经过良好研究的随机梯度下降(SGD)相反,在理解具有DP约束的SGDA的概括(实用程序)方面几乎没有工作。在本文中,我们使用算法稳定性方法在不同的设置中建立DP-SGDA的概括(实用程序)。特别是,对于凸 - 凸环设置,我们证明DP-SGDA可以在平滑和非平滑案例中都可以根据弱原始二元人群风险获得最佳的效用率。据我们所知,这是在非平滑案例中DP-SGDA的第一个已知结果。我们进一步在非convex-rong-concave环境中提供了实用性分析,这是原始人口风险的首个已知结果。即使在非私有设置中,此非convex设置的收敛和概括结果也是新的。最后,进行了数值实验,以证明DP-SGDA在凸和非凸病例中的有效性。
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成对学习是指损失函数取决于一对情况的学习任务。它实例化了许多重要的机器学习任务,如双级排名和度量学习。一种流行的方法来处理成对学习中的流数据是在线梯度下降(OGD)算法,其中需要将当前实例配对以前具有足够大的尺寸的先前实例的电流实例,因此遭受可扩展性问题。在本文中,我们提出了用于成对学习的简单随机和在线梯度下降方法。与现有研究的显着差异是,我们仅将当前实例与前一个构建梯度方向配对,这在存储和计算复杂性中是有效的。我们为凸和非凸起的展示结果,优化和泛化误差界以及平滑和非光滑问题都开发了新颖的稳定性结果,优化和泛化误差界限。我们引入了新颖的技术来解耦模型的依赖性和前一个例子在优化和泛化分析中。我们的研究解决了使用具有非常小的固定尺寸的缓冲集开发OGD的有意义的泛化范围的开放问题。我们还扩展了我们的算法和稳定性分析,以便为成对学习开发差异私有的SGD算法,这显着提高了现有结果。
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非接触式粒子操纵(NPM)技术将人类的分析能力大大扩展到了微观和纳米量表,这反过来又大大促进了材料科学和生命科学的发展。尽管从机器人的角度来看,通过电力,磁性和光场取得了巨大的成功,但它仍然是劳动密集型操作,因为在早期准备阶段,专业人力援助以某种方式是强制性的。因此,出现运动颗粒的自动非接触夹捕获是值得的,特别是对于粒子样品罕见,脆弱或接触敏感的应用。利用最新的动态声场调节技术,尤其是通过从微尺度到亚中心尺度的声学操纵的巨大可扩展性,我们提出了一个自动化的非接触式微粒诱捕,该非接触式捕获具有超声梯级系统和显微镜系统和显微镜系统的移动微粒本文的视觉。据我们所知,这项工作的主要贡献是首次通过诉诸机器人方法来实现声学NPM场中完全自动化的微颗粒捕获。简而言之,通过参考其计算和生成的声学陷阱区域来观察并通过双眼微观视觉系统观察并预测粒子的移动状态。在这项工作中,非连接机器人最终效应器的手眼关系问题也解决了。实验证明了这项工作的有效性。
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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.
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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.
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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.
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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.
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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.
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Benefiting from the intrinsic supervision information exploitation capability, contrastive learning has achieved promising performance in the field of deep graph clustering recently. However, we observe that two drawbacks of the positive and negative sample construction mechanisms limit the performance of existing algorithms from further improvement. 1) The quality of positive samples heavily depends on the carefully designed data augmentations, while inappropriate data augmentations would easily lead to the semantic drift and indiscriminative positive samples. 2) The constructed negative samples are not reliable for ignoring important clustering information. To solve these problems, we propose a Cluster-guided Contrastive deep Graph Clustering network (CCGC) by mining the intrinsic supervision information in the high-confidence clustering results. Specifically, instead of conducting complex node or edge perturbation, we construct two views of the graph by designing special Siamese encoders whose weights are not shared between the sibling sub-networks. Then, guided by the high-confidence clustering information, we carefully select and construct the positive samples from the same high-confidence cluster in two views. Moreover, to construct semantic meaningful negative sample pairs, we regard the centers of different high-confidence clusters as negative samples, thus improving the discriminative capability and reliability of the constructed sample pairs. Lastly, we design an objective function to pull close the samples from the same cluster while pushing away those from other clusters by maximizing and minimizing the cross-view cosine similarity between positive and negative samples. Extensive experimental results on six datasets demonstrate the effectiveness of CCGC compared with the existing state-of-the-art algorithms.
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