This paper is about a curious phenomenon. Suppose we have a data matrix, which is the superposition of a low-rank component and a sparse component. Can we recover each component individually? We prove that under some suitable assumptions, it is possible to recover both the low-rank and the sparse components exactly by solving a very convenient convex program called Principal Component Pursuit; among all feasible decompositions, simply minimize a weighted combination of the nuclear norm and of the 1 norm. This suggests the possibility of a principled approach to robust principal component analysis since our methodology and results assert that one can recover the principal components of a data matrix even though a positive fraction of its entries are arbitrarily corrupted. This extends to the situation where a fraction of the entries are missing as well. We discuss an algorithm for solving this optimization problem, and present applications in the area of video surveillance, where our methodology allows for the detection of objects in a cluttered background, and in the area of face recognition, where it offers a principled way of removing shadows and specularities in images of faces.
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We consider a problem of considerable practical interest: the recovery of a data matrix from a sampling of its entries. Suppose that we observe m entries selected uniformly at random from a matrix M . Can we complete the matrix and recover the entries that we have not seen?We show that one can perfectly recover most low-rank matrices from what appears to be an incomplete set of entries. We prove that if the number m of sampled entries obeys m ≥ C n 1.2 r log n for some positive numerical constant C, then with very high probability, most n × n matrices of rank r can be perfectly recovered by solving a simple convex optimization program. This program finds the matrix with minimum nuclear norm that fits the data. The condition above assumes that the rank is not too large. However, if one replaces the 1.2 exponent with 1.25, then the result holds for all values of the rank. Similar results hold for arbitrary rectangular matrices as well. Our results are connected with the recent literature on compressed sensing, and show that objects other than signals and images can be perfectly reconstructed from very limited information.
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在本文中,我们详细阐述了基于旋转的迭代高斯rbig的扩展,这使图像高斯化成为可能。尽管RBIG已成功应用于许多任务,但它仅限于中等维度数据(按千维数据)。在图像中,其应用程序仅限于小图像贴片或孤立的像素,因为RBIG中的旋转基于主或独立的组件分析,并且这些转换很难学习和扩展。在这里,我们提出\ emph {卷积rbig}:通过强加rbig中的旋转是卷积来减轻此问题的扩展。我们建议通过优化使用转置卷积操作的输入和转换转换的近似反向来学习卷积旋转(即正交卷积)。此外,我们建议在学习这些正规卷积方面不同。例如,激活中施加稀疏性会导致一种转换,该转换将卷积独立的组件分析扩展到多层体系结构。我们还强调了如何从\ emph {卷积rbig}获得数据的统计属性(例如多元互信息)。我们通过简单的纹理合成示例来说明转换的行为,并通过可视化刺激来分析其属性,从而最大程度地提高某些特征和层中的响应。
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已经引入了生成流量网络(GFlowNETS)作为在主动学习背景下采样多样化候选的方法,具有培训目标,其使它们与给定奖励功能成比例地进行比例。在本文中,我们显示了许多额外的GFLOWN的理论特性。它们可用于估计联合概率分布和一些变量未指定的相应边际分布,并且特别感兴趣地,可以代表像集合和图形的复合对象的分布。 Gflownets摊销了通常通过计算昂贵的MCMC方法在单个但训练有素的生成通行证中进行的工作。它们还可用于估计分区功能和自由能量,给定子集(子图)的超标(超图)的条件概率,以及给定集合(图)的所有超标仪(超图)的边际分布。我们引入了熵和相互信息估计的变体,从帕累托前沿采样,与奖励最大化策略的连接,以及随机环境的扩展,连续动作和模块化能量功能。
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我们介绍了学习然后测试,校准机器学习模型的框架,使其预测满足明确的,有限样本统计保证,无论底层模型如何和(未知)数据生成分布。框架地址,以及在其他示例中,在多标签分类中的错误发现速率控制,在实例分割中交叉联盟控制,以及同时控制分类或回归中的异常检测和置信度覆盖的类型误差。为实现这一目标,我们解决了一个关键的技术挑战:控制不一定单调的任意风险。我们的主要洞察力是将风险控制问题重新构建为多个假设检测,使技术和数学论据不同于先前文献中的技术。我们使用我们的框架为多个核心机器学习任务提供新的校准方法,在计算机视觉中具有详细的工作示例。
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决策树学习是机器学习中广泛使用的方法,在需要简洁明了的模型的应用中受到青睐。传统上,启发式方法用于快速生产具有相当高准确性的模型。然而,一个普遍的批评是,从精度和大小方面,所产生的树可能不一定是数据的最佳表示。近年来,这激发了最佳分类树算法的发展,这些算法与执行一系列本地最佳决策的启发式方法相比,在全球范围内优化决策树。我们遵循这一工作线,并提供了一种基于动态编程和搜索的最佳分类树的新颖算法。我们的算法支持对树的深度和节点数量的约束。我们方法的成功归因于一系列专门技术,这些技术利用了分类树独有的属性。传统上,最佳分类树的算法受到了高运行时的困扰和有限的可伸缩性,但我们在一项详细的实验研究中表明,我们的方法仅使用最先进的时间所需的时间,并且可以处理数十个数据集的数据集在数千个实例中,提供了几个数量级的改进,并特别有助于实现最佳决策树的实现。
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This paper considers the model problem of reconstructing an object from incomplete frequency samples. Consider a discrete-time signal f ∈ C N and a randomly chosen set of frequencies Ω of mean size τ N . Is it possible to reconstruct f from the partial knowledge of its Fourier coefficients on the set Ω?A typical result of this paper is as follows: for each M > 0, suppose that f obeysthen with probability at least 1 − O(N −M ), f can be reconstructed exactly as the solution to the ℓ 1 minimization problem min g N −1 t=0 |g(t)|, s.t. ĝ(ω) = f (ω) for all ω ∈ Ω.In short, exact recovery may be obtained by solving a convex optimization problem.We give numerical values for α which depends on the desired probability of success; except for the logarithmic factor, the condition on the size of the support is sharp.The methodology extends to a variety of other setups and higher dimensions. For example, we show how one can reconstruct a piecewise constant (one or two-dimensional) object from incomplete frequency samples-provided that the number of jumps (discontinuities) obeys the condition above-by minimizing other convex functionals such as the total-variation of f .
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Practitioners use Hidden Markov Models (HMMs) in different problems for about sixty years. Besides, Conditional Random Fields (CRFs) are an alternative to HMMs and appear in the literature as different and somewhat concurrent models. We propose two contributions. First, we show that basic Linear-Chain CRFs (LC-CRFs), considered as different from the HMMs, are in fact equivalent to them in the sense that for each LC-CRF there exists a HMM - that we specify - whom posterior distribution is identical to the given LC-CRF. Second, we show that it is possible to reformulate the generative Bayesian classifiers Maximum Posterior Mode (MPM) and Maximum a Posteriori (MAP) used in HMMs, as discriminative ones. The last point is of importance in many fields, especially in Natural Language Processing (NLP), as it shows that in some situations dropping HMMs in favor of CRFs was not necessary.
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We demonstrate a proof-of-concept of a large language model conducting corporate lobbying related activities. We use an autoregressive large language model (OpenAI's text-davinci-003) to determine if proposed U.S. Congressional bills are relevant to specific public companies and provide explanations and confidence levels. For the bills the model deems as relevant, the model drafts a letter to the sponsor of the bill in an attempt to persuade the congressperson to make changes to the proposed legislation. We use hundreds of ground-truth labels of the relevance of a bill to a company to benchmark the performance of the model, which outperforms the baseline of predicting the most common outcome of irrelevance. However, we test the ability to determine the relevance of a bill with the previous OpenAI GPT-3 model (text-davinci-002), which was state-of-the-art on many language tasks until text-davinci-003 was released on November 28, 2022. The performance of text-davinci-002 is worse than simply always predicting that a bill is irrelevant to a company. These results suggest that, as large language models continue to improve core natural language understanding capabilities, performance on corporate lobbying related tasks will continue to improve. We then discuss why this could be problematic for societal-AI alignment.
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In the past years, deep learning has seen an increase of usage in the domain of histopathological applications. However, while these approaches have shown great potential, in high-risk environments deep learning models need to be able to judge their own uncertainty and be able to reject inputs when there is a significant chance of misclassification. In this work, we conduct a rigorous evaluation of the most commonly used uncertainty and robustness methods for the classification of Whole-Slide-Images under domain shift using the H\&E stained Camelyon17 breast cancer dataset. Although it is known that histopathological data can be subject to strong domain shift and label noise, to our knowledge this is the first work that compares the most common methods for uncertainty estimation under these aspects. In our experiments, we compare Stochastic Variational Inference, Monte-Carlo Dropout, Deep Ensembles, Test-Time Data Augmentation as well as combinations thereof. We observe that ensembles of methods generally lead to higher accuracies and better calibration and that Test-Time Data Augmentation can be a promising alternative when choosing an appropriate set of augmentations. Across methods, a rejection of the most uncertain tiles leads to a significant increase in classification accuracy on both in-distribution as well as out-of-distribution data. Furthermore, we conduct experiments comparing these methods under varying conditions of label noise. We observe that the border regions of the Camelyon17 dataset are subject to label noise and evaluate the robustness of the included methods against different noise levels. Lastly, we publish our code framework to facilitate further research on uncertainty estimation on histopathological data.
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