强化学习的最新出现为使用这些算法计算的参数估计值创造了强大的统计推断方法的需求。现有的在线学习中统计推断的方法仅限于涉及独立采样观察的设置，而现有的强化学习中统计推断方法（RL）仅限于批处理设置。在线引导程序是一种灵活，有效的方法，用于线性随机近似算法中的统计推断，但在涉及Markov噪声（例如RL）的设置中，其功效尚未探索。在本文中，我们研究了在线引导方法在RL中的统计推断的使用。特别是，我们专注于时间差异（TD）学习和梯度TD（GTD）学习算法，它们本身就是马尔可夫噪声下线性随机近似的特殊实例。该方法在策略评估中的统计推断上表明该方法在分布上是一致的，并且包括数值实验，以证明该算法在跨一系列实际RL环境中在统计推断任务上的有效性。

We study the problem of preserving privacy while still providing high utility in sequential decision making scenarios in a changing environment. We consider abruptly changing environment: the environment remains constant during periods and it changes at unknown time instants. To formulate this problem, we propose a variant of multi-armed bandits called non-stationary stochastic corrupt bandits. We construct an algorithm called SW-KLUCB-CF and prove an upper bound on its utility using the performance measure of regret. The proven regret upper bound for SW-KLUCB-CF is near-optimal in the number of time steps and matches the best known bound for analogous problems in terms of the number of time steps and the number of changes. Moreover, we present a provably optimal mechanism which can guarantee the desired level of local differential privacy while providing high utility.

The existing methods for video anomaly detection mostly utilize videos containing identifiable facial and appearance-based features. The use of videos with identifiable faces raises privacy concerns, especially when used in a hospital or community-based setting. Appearance-based features can also be sensitive to pixel-based noise, straining the anomaly detection methods to model the changes in the background and making it difficult to focus on the actions of humans in the foreground. Structural information in the form of skeletons describing the human motion in the videos is privacy-protecting and can overcome some of the problems posed by appearance-based features. In this paper, we present a survey of privacy-protecting deep learning anomaly detection methods using skeletons extracted from videos. We present a novel taxonomy of algorithms based on the various learning approaches. We conclude that skeleton-based approaches for anomaly detection can be a plausible privacy-protecting alternative for video anomaly detection. Lastly, we identify major open research questions and provide guidelines to address them.

People living with dementia often exhibit behavioural and psychological symptoms of dementia that can put their and others' safety at risk. Existing video surveillance systems in long-term care facilities can be used to monitor such behaviours of risk to alert the staff to prevent potential injuries or death in some cases. However, these behaviours of risk events are heterogeneous and infrequent in comparison to normal events. Moreover, analyzing raw videos can also raise privacy concerns. In this paper, we present two novel privacy-protecting video-based anomaly detection approaches to detect behaviours of risks in people with dementia. We either extracted body pose information as skeletons and use semantic segmentation masks to replace multiple humans in the scene with their semantic boundaries. Our work differs from most existing approaches for video anomaly detection that focus on appearance-based features, which can put the privacy of a person at risk and is also susceptible to pixel-based noise, including illumination and viewing direction. We used anonymized videos of normal activities to train customized spatio-temporal convolutional autoencoders and identify behaviours of risk as anomalies. We show our results on a real-world study conducted in a dementia care unit with patients with dementia, containing approximately 21 hours of normal activities data for training and 9 hours of data containing normal and behaviours of risk events for testing. We compared our approaches with the original RGB videos and obtained an equivalent area under the receiver operating characteristic curve performance of 0.807 for the skeleton-based approach and 0.823 for the segmentation mask-based approach. This is one of the first studies to incorporate privacy for the detection of behaviours of risks in people with dementia.

Federated Deep Learning frameworks can be used strategically to monitor Land Use locally and infer environmental impacts globally. Distributed data from across the world would be needed to build a global model for Land Use classification. The need for a Federated approach in this application domain would be to avoid transfer of data from distributed locations and save network bandwidth to reduce communication cost. We use a Federated UNet model for Semantic Segmentation of satellite and street view images. The novelty of the proposed architecture is the integration of Knowledge Distillation to reduce communication cost and response time. The accuracy obtained was above 95% and we also brought in a significant model compression to over 17 times and 62 times for street View and satellite images respectively. Our proposed framework has the potential to be a game-changer in real-time tracking of climate change across the planet.

This paper aims to provide an unsupervised modelling approach that allows for a more flexible representation of text embeddings. It jointly encodes the words and the paragraphs as individual matrices of arbitrary column dimension with unit Frobenius norm. The representation is also linguistically motivated with the introduction of a novel similarity metric. The proposed modelling and the novel similarity metric exploits the matrix structure of embeddings. We then go on to show that the same matrices can be reshaped into vectors of unit norm and transform our problem into an optimization problem over the spherical manifold. We exploit manifold optimization to efficiently train the matrix embeddings. We also quantitatively verify the quality of our text embeddings by showing that they demonstrate improved results in document classification, document clustering, and semantic textual similarity benchmark tests.

We introduce SketchySGD, a stochastic quasi-Newton method that uses sketching to approximate the curvature of the loss function. Quasi-Newton methods are among the most effective algorithms in traditional optimization, where they converge much faster than first-order methods such as SGD. However, for contemporary deep learning, quasi-Newton methods are considered inferior to first-order methods like SGD and Adam owing to higher per-iteration complexity and fragility due to inexact gradients. SketchySGD circumvents these issues by a novel combination of subsampling, randomized low-rank approximation, and dynamic regularization. In the convex case, we show SketchySGD with a fixed stepsize converges to a small ball around the optimum at a faster rate than SGD for ill-conditioned problems. In the non-convex case, SketchySGD converges linearly under two additional assumptions, interpolation and the Polyak-Lojaciewicz condition, the latter of which holds with high probability for wide neural networks. Numerical experiments on image and tabular data demonstrate the improved reliability and speed of SketchySGD for deep learning, compared to standard optimizers such as SGD and Adam and existing quasi-Newton methods.

不断增加的材料科学文章使得很难从已发表的文献中推断化学结构 - 培训关系。我们使用自然语言处理（NLP）方法从聚合物文献的摘要中自动提取材料属性数据。作为我们管道的组成部分，我们使用240万材料科学摘要培训了一种语言模型的材料，该材料模型在用作文本编码器时，在五分之三命名实体识别数据集中的其他基线模型都优于其他基线模型。使用此管道，我们在60小时内从约130,000个摘要中获得了约300,000个物质记录。分析了提取的数据，分析了各种应用，例如燃料电池，超级电容器和聚合物太阳能电池，以恢复非平凡的见解。通过我们的管道提取的数据可通过https://polymerscholar.org的Web平台提供，该数据可方便地定位摘要中记录的材料属性数据。这项工作证明了自动管道的可行性，该管道从已发布的文献开始，并以一组完整的提取物质属性信息结束。

我们研究了在约束强化学习中有效探索的后验抽样方法。或者，对于现有算法，我们提出了两种简单的算法，这些算法在统计上更有效，更简单地实现和计算便宜。第一种算法基于CMDP的线性公式，第二算法利用CMDP的鞍点公式。我们的经验结果表明，尽管具有简单性，但后取样可实现最先进的表现，在某些情况下，采样明显优于乐观算法。

更多数据有助于我们推广到任务。但是实际数据集可以包含分布（OOD）数据；这可以以异质性的形式出现，例如类内变异性，也可以以时间变化或概念漂移的形式出现。我们在此类问题上展示了一种反直觉现象：任务的概括误差可能是OOD样本数量的非单调函数；少数OOD样品可以改善概括，但是如果OOD样品的数量超出了阈值，则概括误差可能会恶化。我们还表明，如果我们知道哪些样品是OOD，则使用目标和OOD样品之间的加权目标确保概括误差单调减少。我们使用线性分类器在CIFAR-10上的合成数据集和中型神经网络上使用线性分类器演示和分析了此问题。