This paper studies the quantization of heavy-tailed data in some fundamental statistical estimation problems, where the underlying distributions have bounded moments of some order. We propose to truncate and properly dither the data prior to a uniform quantization. Our major standpoint is that (near) minimax rates of estimation error are achievable merely from the quantized data produced by the proposed scheme. In particular, concrete results are worked out for covariance estimation, compressed sensing, and matrix completion, all agreeing that the quantization only slightly worsens the multiplicative factor. Besides, we study compressed sensing where both covariate (i.e., sensing vector) and response are quantized. Under covariate quantization, although our recovery program is non-convex because the covariance matrix estimator lacks positive semi-definiteness, all local minimizers are proved to enjoy near optimal error bound. Moreover, by the concentration inequality of product process and covering argument, we establish near minimax uniform recovery guarantee for quantized compressed sensing with heavy-tailed noise.
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在本文中,我们研究了经验$ \ ell_2 $最小化(erm)的估计性能(标准)阶段检索(NPR),由$ y_k = | \ alpha_k^*x_0 |^2+\ eta_k $,或嘈杂的广义阶段检索(NGPR)以$ y_k = x_0^*a_kx_0 + \ eta_k $,其中$ x_0 \ in \ mathbb {k}^d $是所需的信号,$ n $是样本大小,$ \ eta =(\ eta_1,...,\ eta_n)^\ top $是噪声向量。我们在不同的噪声模式下建立了新的错误界限,我们的证明对$ \ mathbb {k} = \ mathbb {r} $和$ \ mathbb {k} = \ mathbb {c} $有效。在任意噪声向量$ \ eta $下的NPR中,我们得出了一个新的错误$ o \ big(\ | \ eta \ | _ \ | _ \ infty \ sqrt {\ frac {d} {1}^\ top \ eta |} {n} \ big)$,它比当前已知的一个$ o \ big(\ frac {\ | \ eTa \ |} {\ sqrt {\ sqrt {n}} \ big big )$在许多情况下。在NGPR中,我们显示了$ o \ big(\ | \ eta \ | \ frac {\ sqrt {d}}} {n} {n} \ big)$ for nutary $ \ eta $。在这两个问题上,任意噪声的范围立即引起$ \ tilde {o}(\ sqrt {\ frac {d} {n}}}})$,用于次高斯或次指数随机噪声,带有一些常规但不可吻的去除或削弱的假设(例如,独立或均值均值的条件)。此外,我们首次尝试在假定$ l $ -th时刻的重尾随机噪声下进行ERM。为了实现偏见和差异之间的权衡,我们截断了响应并提出了相应的稳健ERM估计器,该估计量具有保证$ \ tilde {o} \ big(\ big [\ sqrt {\ frac {\ frac {d}) {n}} \ big]^{1-1/l} \ big)$在NPR,NGPR中。所有错误都直接扩展到等级$ r $矩阵恢复的更普遍的问题,这些结果得出的结论是,全级框架$ \ {a_k \} _ {k = 1}^n $ in ngpr是比级别1帧$ \ {\ alpha_k \ alpha_k^*\} _ {k = 1}^n $在npr中更强大。提出了广泛的实验结果,以说明我们的理论发现。
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在本文中,我们提出了一种均匀抖动的一位量化方案,以进行高维统计估计。该方案包含截断,抖动和量化,作为典型步骤。作为规范示例,量化方案应用于三个估计问题:稀疏协方差矩阵估计,稀疏线性回归和矩阵完成。我们研究了高斯和重尾政权,假定重尾数据的基本分布具有有限的第二或第四刻。对于每个模型,我们根据一位量化的数据提出新的估计器。在高斯次级政权中,我们的估计器达到了对数因素的最佳最小速率,这表明我们的量化方案几乎没有额外的成本。在重尾状态下,虽然我们的估计量基本上变慢,但这些结果是在这种单位量化和重型尾部设置中的第一个结果,或者比现有可比结果表现出显着改善。此外,我们为一位压缩传感和一位矩阵完成的问题做出了巨大贡献。具体而言,我们通过凸面编程将一位压缩感传感扩展到次高斯甚至是重尾传感向量。对于一位矩阵完成,我们的方法与标准似然方法基本不同,并且可以处理具有未知分布的预量化随机噪声。提出了有关合成数据的实验结果,以支持我们的理论分析。
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在本文中,我们将颜色图像插入作为纯季基矩阵完成问题。在文献中,季节矩阵完成的理论保证并不确定。我们的主要目的是提出一个新的最小化问题,并将核标准和三个通道之间的二次损失相结合。为了填补理论空缺,我们获得了在干净和损坏的政权中绑定的错误,这依赖于四元素矩阵的一些新结果。在强大的完成中考虑了一般的高斯噪音,所有观察都被损坏。由于界限的动机,我们建议通过二次损失中的跨通道重量来处理不平衡或相关的噪声,这是重新平衡噪声水平或消除噪声相关性的主要目的。提供了有关合成和颜色图像数据的广泛实验结果,以确认和证明我们的理论发现。
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相关神经回路的功能改变是在一定时期的药物成瘾中发生的。这些重大变化也通过分析fMRI揭示。然而,由于fMRI的高维度和信噪比差,因此对于图形识别和尼古丁成瘾(NA)和健康控制之间的图形识别和区域级生物标志物检测任务编码有效且健壮的大脑区域嵌入是一项挑战。 HC)组。在这项工作中,我们将大鼠脑的fMRI表示为具有生物学属性的图形,并提出了一种新型特征选择的图形空间注意网络(FGSAN),以提取成瘾的生物标志物并从这些大脑网络中识别。特别是,使用图形空间注意编码器来捕获具有空间信息的时空脑网络的特征。该方法同时采用贝叶斯特征选择策略,以通过约束功能来优化模型并改善分类任务。与成瘾相关的神经成像数据集进行的实验表明,所提出的模型可以获得卓越的性能并检测与成瘾的神经回路相关的可解释的生物标志物。
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不同类型的神经影像数据的跨模式融合显示了预测阿尔茨海默氏病(AD)进展的巨大希望。但是,在神经成像中应用的大多数现有方法无法有效地融合来自多模式神经图像的功能和结构信息。在这项工作中,提出了一种新型的跨模式变压器生成对抗网络(CT-GAN),以融合包含在静止状态功能磁共振成像(RS-FMRI)中的功能信息(RS-FMRI),并包含在扩散张量图像(DTI)中包含的结构信息。开发的双重注意机制可以有效地匹配功能信息,并最大程度地提高从RS-FMRI和DTI提取互补信息的能力。通过捕获结构特征和功能特征之间的深层互补信息,提出的CT-GAN可以检测到与AD相关的大脑连接性,可以用作AD的生物标志物。实验结果表明,所提出的模型不仅可以改善分类性能,而且还可以有效地检测与广告相关的大脑连接性。
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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.
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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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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.
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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.
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