对成对比较的排名聚集在选举,体育比赛,建议和信息检索中表现出了令人鼓舞的结果。但是,与众多有关计算和统计特征的研究工作相反,对这种算法的安全问题几乎没有关注。在巨额利润的推动下,潜在的对手具有强大的动力和动力来操纵排名清单。同时,文献中没有很好地研究等级聚集方法的内在脆弱性。为了充分了解可能的风险,我们专注于有目的的对手,他们希望通过修改本文中的成对数据来指定汇总结果。从动力学系统的角度来看,具有目标排名列表的攻击行为是属于对手和受害者组成的固定点。为了执行目标攻击,我们将对手和受害者之间的相互作用作为游戏理论框架,由两个连续的操作员组成,同时建立了NASH平衡。然后,构建了针对Hodgerank和RankCentrality的两个程序,以产生原始数据的修改。此外,我们证明,一旦对手掌握了完整的信息,受害者将产生目标排名列表。值得注意的是,所提出的方法允许对手只保留不完整的信息或不完美的反馈并执行有目的的攻击。一系列玩具模拟和几个现实世界数据实验证明了建议的目标攻击策略的有效性。这些实验结果表明,所提出的方法可以实现攻击者的目标,即扰动排名列表的领先候选人是对手指定的。
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随机游戏的学习可以说是多功能钢筋学习(MARL)中最标准和最基本的环境。在本文中,我们考虑在非渐近制度的随机游戏中分散的Marl。特别是,我们在大量的一般总和随机游戏(SGS)中建立了完全分散的Q学习算法的有限样本复杂性 - 弱循环SGS,包括对所有代理商的普通合作MARL设置具有相同的奖励(马尔可夫团队问题是一个特例。我们专注于实用的同时具有挑战性地设置完全分散的Marl,既不奖励也没有其他药剂的作用,每个试剂都可以观察到。事实上,每个特工都完全忘记了其他决策者的存在。表格和线性函数近似情况都已考虑。在表格设置中,我们分析了分散的Q学习算法的样本复杂性,以收敛到马尔可夫完美均衡(NASH均衡)。利用线性函数近似,结果用于收敛到线性近似平衡 - 我们提出的均衡的新概念 - 这描述了每个代理的策略是线性空间内的最佳回复(到其他代理)。还提供了数值实验,用于展示结果。
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半监督域适应(SSDA)是一种具有挑战性的问题,需要克服1)以朝向域的较差的数据和2)分布换档的方法。不幸的是,由于培训数据偏差朝标标样本训练,域适应(DA)和半监督学习(SSL)方法的简单组合通常无法解决这两个目的。在本文中,我们介绍了一种自适应结构学习方法,以规范SSL和DA的合作。灵感来自多视图学习,我们建议的框架由共享特征编码器网络和两个分类器网络组成,用于涉及矛盾的目的。其中,其中一个分类器被应用于组目标特征以提高级别的密度,扩大了鲁棒代表学习的分类集群的间隙。同时,其他分类器作为符号器,试图散射源功能以增强决策边界的平滑度。目标聚类和源扩展的迭代使目标特征成为相应源点的扩张边界内的封闭良好。对于跨域特征对齐和部分标记的数据学习的联合地址,我们应用最大平均差异(MMD)距离最小化和自培训(ST)将矛盾结构投影成共享视图以进行可靠的最终决定。对标准SSDA基准的实验结果包括Domainnet和Office-Home,展示了我们对最先进的方法的方法的准确性和稳健性。
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Mapping with uncertainty representation is required in many research domains, such as localization and sensor fusion. Although there are many uncertainty explorations in pose estimation of an ego-robot with map information, the quality of the reference maps is often neglected. To avoid the potential problems caused by the errors of maps and a lack of the uncertainty quantification, an adequate uncertainty measure for the maps is required. In this paper, uncertain building models with abstract map surface using Gaussian Process (GP) is proposed to measure the map uncertainty in a probabilistic way. To reduce the redundant computation for simple planar objects, extracted facets from a Gaussian Mixture Model (GMM) are combined with the implicit GP map while local GP-block techniques are used as well. The proposed method is evaluated on LiDAR point clouds of city buildings collected by a mobile mapping system. Compared to the performances of other methods such like Octomap, Gaussian Process Occupancy Map (GPOM) and Bayersian Generalized Kernel Inference (BGKOctomap), our method has achieved higher Precision-Recall AUC for evaluated buildings.
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How to solve the data scarcity problem for end-to-end speech-to-text translation (ST)? It's well known that data augmentation is an efficient method to improve performance for many tasks by enlarging the dataset. In this paper, we propose Mix at three levels for Speech Translation (M^3ST) method to increase the diversity of the augmented training corpus. Specifically, we conduct two phases of fine-tuning based on a pre-trained model using external machine translation (MT) data. In the first stage of fine-tuning, we mix the training corpus at three levels, including word level, sentence level and frame level, and fine-tune the entire model with mixed data. At the second stage of fine-tuning, we take both original speech sequences and original text sequences in parallel into the model to fine-tune the network, and use Jensen-Shannon divergence to regularize their outputs. Experiments on MuST-C speech translation benchmark and analysis show that M^3ST outperforms current strong baselines and achieves state-of-the-art results on eight directions with an average BLEU of 29.9.
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Positive-Unlabeled (PU) learning tries to learn binary classifiers from a few labeled positive examples with many unlabeled ones. Compared with ordinary semi-supervised learning, this task is much more challenging due to the absence of any known negative labels. While existing cost-sensitive-based methods have achieved state-of-the-art performances, they explicitly minimize the risk of classifying unlabeled data as negative samples, which might result in a negative-prediction preference of the classifier. To alleviate this issue, we resort to a label distribution perspective for PU learning in this paper. Noticing that the label distribution of unlabeled data is fixed when the class prior is known, it can be naturally used as learning supervision for the model. Motivated by this, we propose to pursue the label distribution consistency between predicted and ground-truth label distributions, which is formulated by aligning their expectations. Moreover, we further adopt the entropy minimization and Mixup regularization to avoid the trivial solution of the label distribution consistency on unlabeled data and mitigate the consequent confirmation bias. Experiments on three benchmark datasets validate the effectiveness of the proposed method.Code available at: https://github.com/Ray-rui/Dist-PU-Positive-Unlabeled-Learning-from-a-Label-Distribution-Perspective.
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We address the problem of synthesizing novel views from a monocular video depicting a complex dynamic scene. State-of-the-art methods based on temporally varying Neural Radiance Fields (aka dynamic NeRFs) have shown impressive results on this task. However, for long videos with complex object motions and uncontrolled camera trajectories, these methods can produce blurry or inaccurate renderings, hampering their use in real-world applications. Instead of encoding the entire dynamic scene within the weights of an MLP, we present a new approach that addresses these limitations by adopting a volumetric image-based rendering framework that synthesizes new viewpoints by aggregating features from nearby views in a scene-motion-aware manner. Our system retains the advantages of prior methods in its ability to model complex scenes and view-dependent effects, but also enables synthesizing photo-realistic novel views from long videos featuring complex scene dynamics with unconstrained camera trajectories. We demonstrate significant improvements over state-of-the-art methods on dynamic scene datasets, and also apply our approach to in-the-wild videos with challenging camera and object motion, where prior methods fail to produce high-quality renderings. Our project webpage is at dynibar.github.io.
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Traditional machine learning follows a close-set assumption that the training and test set share the same label space. While in many practical scenarios, it is inevitable that some test samples belong to unknown classes (open-set). To fix this issue, Open-Set Recognition (OSR), whose goal is to make correct predictions on both close-set samples and open-set samples, has attracted rising attention. In this direction, the vast majority of literature focuses on the pattern of open-set samples. However, how to evaluate model performance in this challenging task is still unsolved. In this paper, a systematic analysis reveals that most existing metrics are essentially inconsistent with the aforementioned goal of OSR: (1) For metrics extended from close-set classification, such as Open-set F-score, Youden's index, and Normalized Accuracy, a poor open-set prediction can escape from a low performance score with a superior close-set prediction. (2) Novelty detection AUC, which measures the ranking performance between close-set and open-set samples, ignores the close-set performance. To fix these issues, we propose a novel metric named OpenAUC. Compared with existing metrics, OpenAUC enjoys a concise pairwise formulation that evaluates open-set performance and close-set performance in a coupling manner. Further analysis shows that OpenAUC is free from the aforementioned inconsistency properties. Finally, an end-to-end learning method is proposed to minimize the OpenAUC risk, and the experimental results on popular benchmark datasets speak to its effectiveness.
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Precision-Recall曲线(AUPRC)下区域的随机优化是机器学习的关键问题。尽管已经对各种算法进行了广泛研究以进行AUPRC优化,但仅在多Query情况下保证了概括。在这项工作中,我们介绍了随机AUPRC优化的一次性概括中的第一个试验。对于更庞大的概括范围,我们专注于算法依赖性概括。我们目的地都有算法和理论障碍。从算法的角度来看,我们注意到,仅当采样策略偏见时,大多数现有随机估计器才会偏向,并且由于不可兼容性而不稳定。为了解决这些问题,我们提出了一个具有卓越稳定性的采样率不变的无偏随机估计器。最重要的是,AUPRC优化是作为组成优化问题配制的,并提出了随机算法来解决此问题。从理论的角度来看,算法依赖性概括分析的标准技术不能直接应用于这种列表的组成优化问题。为了填补这一空白,我们将模型稳定性从实例损失扩展到列表损失,并弥合相应的概括和稳定性。此外,我们构建状态过渡矩阵以描述稳定性的复发,并通过矩阵频谱简化计算。实际上,关于三个图像检索数据集的实验结果谈到了我们框架的有效性和健全性。
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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。
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