Contextual bandit has been widely used for sequential decision-making based on the current contextual information and historical feedback data. In modern applications, such context format can be rich and can often be formulated as a matrix. Moreover, while existing bandit algorithms mainly focused on reward-maximization, less attention has been paid to the statistical inference. To fill in these gaps, in this work we consider a matrix contextual bandit framework where the true model parameter is a low-rank matrix, and propose a fully online procedure to simultaneously make sequential decision-making and conduct statistical inference. The low-rank structure of the model parameter and the adaptivity nature of the data collection process makes this difficult: standard low-rank estimators are not fully online and are biased, while existing inference approaches in bandit algorithms fail to account for the low-rankness and are also biased. To address these, we introduce a new online doubly-debiasing inference procedure to simultaneously handle both sources of bias. In theory, we establish the asymptotic normality of the proposed online doubly-debiased estimator and prove the validity of the constructed confidence interval. Our inference results are built upon a newly developed low-rank stochastic gradient descent estimator and its non-asymptotic convergence result, which is also of independent interest.

Positioning with one inertial measurement unit and one ranging sensor is commonly thought to be feasible only when trajectories are in certain patterns ensuring observability. For this reason, to pursue observable patterns, it is required either exciting the trajectory or searching key nodes in a long interval, which is commonly highly nonlinear and may also lack resilience. Therefore, such a positioning approach is still not widely accepted in real-world applications. To address this issue, this work first investigates the dissipative nature of flying robots considering aerial drag effects and re-formulates the corresponding positioning problem, which guarantees observability almost surely. On this basis, a dimension-reduced wriggling estimator is proposed accordingly. This estimator slides the estimation horizon in a stepping manner, and output matrices can be approximately evaluated based on the historical estimation sequence. The computational complexity is then further reduced via a dimension-reduction approach using polynomial fittings. In this way, the states of robots can be estimated via linear programming in a sufficiently long interval, and the degree of observability is thereby further enhanced because an adequate redundancy of measurements is available for each estimation. Subsequently, the estimator's convergence and numerical stability are proven theoretically. Finally, both indoor and outdoor experiments verify that the proposed estimator can achieve decimeter-level precision at hundreds of hertz per second, and it is resilient to sensors' failures. Hopefully, this study can provide a new practical approach for self-localization as well as relative positioning of cooperative agents with low-cost and lightweight sensors.

阴影对于逼真的图像合成至关重要。基于物理的阴影渲染方法需要3D几何形状，这并不总是可用。基于深度学习的阴影综合方法从光信息到对象的阴影中学习映射，而无需明确建模阴影几何形状。尽管如此，它们仍然缺乏控制，并且容易出现视觉伪像。我们介绍了Pixel Heigh，这是一种新颖的几何表示，它编码对象，地面和相机姿势之间的相关性。像素高度可以根据3D几何形状计算，并在2D图像上手动注释，也可以通过有监督的方法从单视RGB图像中预测。它可用于根据投影几何形状计算2D图像中的硬阴影，从而精确控制阴影的方向和形状。此外，我们提出了一个数据驱动的软影子生成器，以基于软性输入参数将软性应用于硬阴影。定性和定量评估表明，所提出的像素高度显着提高了阴影产生的质量，同时允许可控性。

元学习在现有基准测试基准上的成功取决于以下假设：元训练任务的分布涵盖了元测试任务。经常违反任务不足或非常狭窄的元训练任务分布的应用中的假设会导致记忆或学习者过度拟合。最近的解决方案已追求元训练任务的增强，而同时产生正确和充分虚构任务的问题仍然是一个悬而未决的问题。在本文中，我们寻求一种方法，该方法是通过任务上采样网络从任务表示从任务表示的映射任务。此外，最终的方法将对抗性任务上采样（ATU）命名为足以生成可以通过最大化对抗性损失来最大程度地贡献最新元学习者的任务。在几乎没有正弦的回归和图像分类数据集上，我们从经验上验证了ATU在元测试性能中的最新任务增强策略的明显改善以及上采样任务的质量。

基于部分微分方程的物理模拟通常会生成空间场结果，这些结果可用于计算系统设计和优化系统的特定属性。由于模拟的密集计算负担，替代模型将低维输入映射到空间场通常是基于相对较小的数据集构建的。为了解决预测整个空间场的挑战，流行的核心区域线性线性模型（LMC）可以在高维空间场输出中解散复杂的相关性，并提供准确的预测。但是，如果通过基本函数与潜在过程的线性组合无法很好地近似空间场，则LMC会失败。在本文中，我们通过引入可演化的神经网络来线性化高度复杂和非线性空间场，以便LMC可以轻松地将非线性问题概括为非线性问题，同时保留了放大学性和可伸缩性。几个现实世界的应用程序表明，E-LMC可以有效利用空间相关性，显示出比原始LMC的最大提高约40％，并且表现优于其他最先进的空间场模型。

主动学习旨在选择最具信息丰富的样本，以利用有限的注释预算。大多数现有的工作通过分别在每个数据集上多次重复耗时的模型训练和批量数据选择，遵循麻烦的管道。通过提出本文提出新的一般和有效的主动学习（GEAL）方法，挑战该地位QUO。利用预先培训的大型数据集预先培训的公开模型，我们的方法可以在不同的数据集中对具有相同模型的单通推断进行数据选择过程。为了捕获图像内的微妙本地信息，我们提出了从预先训练网络的中间特征中容易地提取的知识集群。而不是麻烦的批量选择策略，通过在细粒度知识集群级别执行K中心贪婪来选择所有数据样本。整个过程只需要单通式模型推论而不培训或监督，使我们的方法在时间复杂程度明显优于现有技术，从而长达数百次。广泛的实验越来越展示了我们对物体检测，语义分割，深度估计和图像分类方法的有希望的性能。

对象的时间建模是多个对象跟踪（MOT）的关键挑战。现有方法通过通过基于运动和基于外观的相似性启发式方法关联检测来跟踪。关联的后处理性质阻止了视频序列中时间变化的端到端。在本文中，我们提出了MOTR，它扩展了DETR并介绍了轨道查询，以模拟整个视频中的跟踪实例。轨道查询被转移并逐帧更新，以随着时间的推移执行迭代预测。我们提出了曲目感知的标签分配，以训练轨道查询和新生儿对象查询。我们进一步提出了时间聚集网络和集体平均损失，以增强时间关系建模。 Dancetrack上的实验结果表明，MOTR在HOTA度量方面的表现明显优于最先进的方法，字节范围为6.5％。在MOT17上，MOTR在关联性能方面优于我们的并发作品，跟踪器和Transtrack。 MOTR可以作为对时间建模和基于变压器的跟踪器的未来研究的更强基线。代码可在https://github.com/megvii-research/motr上找到。

This paper provides a pair similarity optimization viewpoint on deep feature learning, aiming to maximize the within-class similarity s p and minimize the between-class similarity s n . We find a majority of loss functions, including the triplet loss and the softmax cross-entropy loss, embed s n and s p into similarity pairs and seek to reduce (s n − s p ). Such an optimization manner is inflexible, because the penalty strength on every single similarity score is restricted to be equal. Our intuition is that if a similarity score deviates far from the optimum, it should be emphasized. To this end, we simply re-weight each similarity to highlight the less-optimized similarity scores. It results in a Circle loss, which is named due to its circular decision boundary. The Circle loss has a unified formula for two elemental deep feature learning paradigms, i.e., learning with class-level labels and pair-wise labels. Analytically, we show that the Circle loss offers a more flexible optimization approach towards a more definite convergence target, compared with the loss functions optimizing (s n − s p ). Experimentally, we demonstrate the superiority of the Circle loss on a variety of deep feature learning tasks. On face recognition, person re-identification, as well as several finegrained image retrieval datasets, the achieved performance is on par with the state of the art.

We revisit the one-shot Neural Architecture Search (NAS) paradigm and analyze its advantages over existing NAS approaches. Existing one-shot method, however, is hard to train and not yet effective on large scale datasets like ImageNet. This work propose a Single Path One-Shot model to address the challenge in the training. Our central idea is to construct a simplified supernet, where all architectures are single paths so that weight co-adaption problem is alleviated. Training is performed by uniform path sampling. All architectures (and their weights) are trained fully and equally. Comprehensive experiments verify that our approach is flexible and effective. It is easy to train and fast to search. It effortlessly supports complex search spaces (e.g., building blocks, channel, mixed-precision quantization) and different search constraints (e.g., FLOPs, latency). It is thus convenient to use for various needs. It achieves start-of-the-art performance on the large dataset ImageNet.Equal contribution. This work is done when Haoyuan Mu and Zechun Liu are interns at MEGVII Technology.

There has been significant progress on pose estimation and increasing interests on pose tracking in recent years. At the same time, the overall algorithm and system complexity increases as well, making the algorithm analysis and comparison more difficult. This work provides simple and effective baseline methods. They are helpful for inspiring and evaluating new ideas for the field. State-of-the-art results are achieved on challenging benchmarks. The code will be available at https://github. com/leoxiaobin/pose.pytorch.