计算机视觉是由许多数据集驱动的,这些数据集可用于培训或评估新方法。但是,每个数据集都有不同的类标签,类的视觉定义,遵循特定分布的图像,注释协议等。在本文中,我们探讨了跨数据集之间的视觉语义关系的自动发现。我们想了解数据集中某个类的实例与另一个数据集中另一类的实例有关。他们是否处于身份,父母/孩子的重叠关系中?还是他们之间没有链接?为了找到跨数据集的标签之间的关系,我们根据语言,视觉和两者的组合提出方法。我们的方法可以有效地发现跨数据集和关系类型的标签关系。我们使用这些结果进行更深入的检查,以了解为什么实例相关,找到班级缺失方面,并利用我们的关系来创建更细粒度的注释。我们得出的结论是,不能通过单独查看类的名称来建立标签关系,因为它们在很大程度上取决于每个数据集的构建方式。
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我们解决了转移学习中的集合选择问题:给出了大量的源模型,我们要选择一个模型的集合,在对目标训练集的微调后,在目标测试集上产生最佳性能。由于微调所有可能的合奏是计算禁止的,因此我们目的是使用计算上有效的可转换度量来预测目标数据集的性能。我们提出了用于此任务的几个新的可转换性指标,并在对语义细分的具有挑战性和现实的转移学习设置中进行评估:我们通过考虑涵盖各种图像域的各种数据集来创建一个大型和多样化的源模型池,两种不同架构和两个预训练计划。鉴于此池,我们自动选择子集,以在给定的目标数据集上形成良好的集合。我们将通过我们的方法选择的合奏与两个基线进行比较,该基线选择单个源模型,其中(1)与我们的方法相同;或(2)从包含大源模型的池,每个池具有与集合相似的容量。平均超过17个目标数据集,我们分别以6.0%和2.5%的相对平均值越优于这些基线。
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转移学习已成为利用计算机视觉中预先训练模型的流行方法。然而,在不执行计算上昂贵的微调的情况下,难以量化哪个预先训练的源模型适用于特定目标任务,或者相反地,可以容易地适应预先训练的源模型的任务。在这项工作中,我们提出了高斯Bhattacharyya系数(GBC),一种用于量化源模型和目标数据集之间的可转换性的新方法。在第一步中,我们在由源模型定义的特征空间中嵌入所有目标图像,并表示使用每类高斯。然后,我们使用Bhattacharyya系数估计它们的成对类可分离性,从而产生了一种简单有效的源模型转移到目标任务的程度。我们在数据集和架构选择的上下文中评估GBC在图像分类任务上。此外,我们还对更复杂的语义分割转移性估算任务进行实验。我们证明GBC在语义分割设置中大多数评估标准上的最先进的可转移性度量,匹配图像分类中的数据集转移性的最高方法的性能,并且在图像分类中执行最佳的架构选择问题。
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转移学习可以在源任务上重新使用知识来帮助学习目标任务。一种简单的转移学习形式在当前的最先进的计算机视觉模型中是常见的,即预先训练ILSVRC数据集上的图像分类模型,然后在任何目标任务上进行微调。然而,先前对转移学习的系统研究已经有限,并且预计工作的情况并不完全明白。在本文中,我们对跨越不同的图像域进行了广泛的转移学习实验探索(消费者照片,自主驾驶,空中图像,水下,室内场景,合成,特写镜头)和任务类型(语义分割,物体检测,深度估计,关键点检测)。重要的是,这些都是与现代计算机视觉应用相关的复杂的结构化的输出任务类型。总共执行超过2000年的转移学习实验,包括许多来源和目标来自不同的图像域,任务类型或两者。我们系统地分析了这些实验,了解图像域,任务类型和数据集大小对传输学习性能的影响。我们的研究导致了几个见解和具体建议:(1)对于大多数任务,存在一个显着优于ILSVRC'12预培训的来源; (2)图像领域是实现阳性转移的最重要因素; (3)源数据集应该\ \ emph {include}目标数据集的图像域以获得最佳结果; (4)与此同时,当源任务的图像域比目标的图像域时,我们只观察小的负面影响; (5)跨任务类型的转移可能是有益的,但其成功严重依赖于源和目标任务类型。
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Semantic classes can be either things (objects with a well-defined shape, e.g. car, person) or stuff (amorphous background regions, e.g. grass, sky). While lots of classification and detection works focus on thing classes, less attention has been given to stuff classes. Nonetheless, stuff classes are important as they allow to explain important aspects of an image, including (1) scene type; (2) which thing classes are likely to be present and their location (through contextual reasoning); (3) physical attributes, material types and geometric properties of the scene. To understand stuff and things in context we introduce COCO-Stuff 1 , which augments all 164K images of the COCO 2017 dataset with pixel-wise annotations for 91 stuff classes. We introduce an efficient stuff annotation protocol based on superpixels, which leverages the original thing annotations. We quantify the speed versus quality trade-off of our protocol and explore the relation between annotation time and boundary complexity. Furthermore, we use COCO-Stuff to analyze: (a) the importance of stuff and thing classes in terms of their surface cover and how frequently they are mentioned in image captions; (b) the spatial relations between stuff and things, highlighting the rich contextual relations that make our dataset unique; (c) the performance of a modern semantic segmentation method on stuff and thing classes, and whether stuff is easier to segment than things.
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Even though deep neural networks (DNNs) achieve state-of-the-art results for a number of problems involving genomic data, getting DNNs to explain their decision-making process has been a major challenge due to their black-box nature. One way to get DNNs to explain their reasoning for prediction is via attribution methods which are assumed to highlight the parts of the input that contribute to the prediction the most. Given the existence of numerous attribution methods and a lack of quantitative results on the fidelity of those methods, selection of an attribution method for sequence-based tasks has been mostly done qualitatively. In this work, we take a step towards identifying the most faithful attribution method by proposing a computational approach that utilizes point mutations. Providing quantitative results on seven popular attribution methods, we find Layerwise Relevance Propagation (LRP) to be the most appropriate one for translation initiation, with LRP identifying two important biological features for translation: the integrity of Kozak sequence as well as the detrimental effects of premature stop codons.
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This chapter sheds light on the synaptic organization of the brain from the perspective of computational neuroscience. It provides an introductory overview on how to account for empirical data in mathematical models, implement them in software, and perform simulations reflecting experiments. This path is demonstrated with respect to four key aspects of synaptic signaling: the connectivity of brain networks, synaptic transmission, synaptic plasticity, and the heterogeneity across synapses. Each step and aspect of the modeling and simulation workflow comes with its own challenges and pitfalls, which are highlighted and addressed in detail.
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We present an approach for safe trajectory planning, where a strategic task related to autonomous racing is learned sample-efficient within a simulation environment. A high-level policy, represented as a neural network, outputs a reward specification that is used within the cost function of a parametric nonlinear model predictive controller (NMPC). By including constraints and vehicle kinematics in the NLP, we are able to guarantee safe and feasible trajectories related to the used model. Compared to classical reinforcement learning (RL), our approach restricts the exploration to safe trajectories, starts with a good prior performance and yields full trajectories that can be passed to a tracking lowest-level controller. We do not address the lowest-level controller in this work and assume perfect tracking of feasible trajectories. We show the superior performance of our algorithm on simulated racing tasks that include high-level decision making. The vehicle learns to efficiently overtake slower vehicles and to avoid getting overtaken by blocking faster vehicles.
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We study the fundamental task of outlier-robust mean estimation for heavy-tailed distributions in the presence of sparsity. Specifically, given a small number of corrupted samples from a high-dimensional heavy-tailed distribution whose mean $\mu$ is guaranteed to be sparse, the goal is to efficiently compute a hypothesis that accurately approximates $\mu$ with high probability. Prior work had obtained efficient algorithms for robust sparse mean estimation of light-tailed distributions. In this work, we give the first sample-efficient and polynomial-time robust sparse mean estimator for heavy-tailed distributions under mild moment assumptions. Our algorithm achieves the optimal asymptotic error using a number of samples scaling logarithmically with the ambient dimension. Importantly, the sample complexity of our method is optimal as a function of the failure probability $\tau$, having an additive $\log(1/\tau)$ dependence. Our algorithm leverages the stability-based approach from the algorithmic robust statistics literature, with crucial (and necessary) adaptations required in our setting. Our analysis may be of independent interest, involving the delicate design of a (non-spectral) decomposition for positive semi-definite matrices satisfying certain sparsity properties.
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Syntax is a latent hierarchical structure which underpins the robust and compositional nature of human language. An active line of inquiry is whether large pretrained language models (LLMs) are able to acquire syntax by training on text alone; understanding a model's syntactic capabilities is essential to understanding how it processes and makes use of language. In this paper, we propose a new method, SSUD, which allows for the induction of syntactic structures without supervision from gold-standard parses. Instead, we seek to define formalism-agnostic, model-intrinsic syntactic parses by using a property of syntactic relations: syntactic substitutability. We demonstrate both quantitative and qualitative gains on dependency parsing tasks using SSUD, and induce syntactic structures which we hope provide clarity into LLMs and linguistic representations, alike.
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