Understanding the variations in trading price (volatility), and its response to exogenous information, is a well-researched topic in finance. In this study, we focus on finding stable and accurate volatility predictors for a relatively new asset class of cryptocurrencies, in particular Bitcoin, using deep learning representations of public social media data obtained from Twitter. For our experiments, we extracted semantic information and user statistics from over 30 million Bitcoin-related tweets, in conjunction with 15-minute frequency price data over a horizon of 144 days. Using this data, we built several deep learning architectures that utilized different combinations of the gathered information. For each model, we conducted ablation studies to assess the influence of different components and feature sets over the prediction accuracy. We found statistical evidences for the hypotheses that: (i) temporal convolutional networks perform significantly better than both classical autoregressive models and other deep learning-based architectures in the literature, and (ii) tweet author meta-information, even detached from the tweet itself, is a better predictor of volatility than the semantic content and tweet volume statistics. We demonstrate how different information sets gathered from social media can be utilized in different architectures and how they affect the prediction results. As an additional contribution, we make our dataset public for future research.

高斯工艺（GPS）是贝叶斯非参数模型，由于其准确性和天然不确定性定量（UQ），因此在各种应用中流行。调整GP超参数对于确保预测准确性和不确定性的有效性至关重要。独特地估计多个超参数，例如Matern内核也可能是一个重大挑战。此外，大规模数据集中的培训GPS是一个高度活跃的研究领域：传统的最大似然超参数训练需要二次记忆以形成协方差矩阵并具有立方训练的复杂性。为了解决可扩展的超参数调整问题，我们提出了一种新型算法，该算法估算了Matern内核中的平滑度和长度尺度参数，以提高所得预测不确定性的鲁棒性。使用与超参数估计算法MUYGPS提供的计算框架中的合并预测算法相似的新型损失函数，我们在数值实验中证明了高度可伸缩性，同时保持了高度可伸缩性。

本文重点介绍了静态和时变设置中决策依赖性分布的随机鞍点问题。这些是目标是随机收益函数的预期值，其中随机变量从分布图引起的分布中绘制。对于一般分布地图，即使已知分布是已知的，发现鞍点的问题也是一般的计算繁琐。为了实现易求解的解决方案方法，我们介绍了均衡点的概念 - 这是它们诱导的静止随机最小值问题的马鞍点 - 并为其存在和唯一性提供条件。我们证明，两个类解决方案之间的距离被界定，条件是该目标具有强凸强 - 凹入的收益和Lipschitz连续分布图。我们开发确定性和随机的原始算法，并证明它们对均衡点的收敛性。特别是，通过将来自随机梯度估计器的出现的错误建模为子-Weibull随机变量，我们提供期望的错误界限，并且在每个迭代的高概率中提供的误差;此外，我们向期望和几乎肯定地显示给社区的融合。最后，我们调查了分布地图的条件 - 我们调用相反的混合优势 - 确保目标是强烈的凸强 - 凹陷的。在这种假设下，我们表明原始双算法以类似的方式汇集到鞍座点。

机器学习已成功构建许多顺序决策，作为监督预测，或通过加强学习的最佳决策政策识别。在数据约束的离线设置中，两种方法可能会失败，因为它们假设完全最佳行为或依赖于探索可能不存在的替代方案。我们介绍了一种固有的不同方法，该方法识别出状态空间的可能的“死角”。我们专注于重症监护病房中患者的状况，其中``“医疗死亡端”表明患者将过期，无论所有潜在的未来治疗序列如何。我们假设“治疗安全”为避免与其导致死亡事件的机会成比例的概率成比例的治疗，呈现正式证明，以及作为RL问题的帧发现。然后，我们将三个独立的深度神经模型进行自动化状态建设，死端发现和确认。我们的经验结果发现，死亡末端存在于脓毒症患者的真正临床数据中，并进一步揭示了安全处理与施用的差距。

Deep Generative Models (DGMs) are a popular class of deep learning models which find widespread use because of their ability to synthesize data from complex, high-dimensional manifolds. However, even with their increasing industrial adoption, they haven't been subject to rigorous security and privacy analysis. In this work we examine one such aspect, namely backdoor attacks on DGMs which can significantly limit the applicability of pre-trained models within a model supply chain and at the very least cause massive reputation damage for companies outsourcing DGMs form third parties. While similar attacks scenarios have been studied in the context of classical prediction models, their manifestation in DGMs hasn't received the same attention. To this end we propose novel training-time attacks which result in corrupted DGMs that synthesize regular data under normal operations and designated target outputs for inputs sampled from a trigger distribution. These attacks are based on an adversarial loss function that combines the dual objectives of attack stealth and fidelity. We systematically analyze these attacks, and show their effectiveness for a variety of approaches like Generative Adversarial Networks (GANs) and Variational Autoencoders (VAEs), as well as different data domains including images and audio. Our experiments show that - even for large-scale industry-grade DGMs (like StyleGAN) - our attacks can be mounted with only modest computational effort. We also motivate suitable defenses based on static/dynamic model and output inspections, demonstrate their usefulness, and prescribe a practical and comprehensive defense strategy that paves the way for safe usage of DGMs.

我们在\ textit {躁动不安的多臂土匪}（rmabs）中引入了鲁棒性，这是一个流行的模型，用于在独立随机过程（臂）之间进行约束资源分配。几乎所有RMAB技术都假设随机动力学是精确的。但是，在许多实际设置中，动态是用显着的\ emph {不确定性}估算的，例如，通过历史数据，如果被忽略，这可能会导致不良结果。为了解决这个问题，我们开发了一种算法来计算Minimax遗憾 - RMAB的强大政策。我们的方法使用双oracle框架（\ textit {agent}和\ textit {nature}），通常用于单过程强大的计划，但需要大量的新技术来适应RMAB的组合性质。具体而言，我们设计了深入的强化学习（RL）算法DDLPO，该算法通过学习辅助机构“ $ \ lambda $ -network”来应对组合挑战，并与每手臂的策略网络串联，大大降低了样本复杂性，并确保了融合。普遍关注的DDLPO实现了我们的奖励最大化代理Oracle。然后，我们通过将其作为策略优化器和对抗性性质之间的多代理RL问题提出来解决具有挑战性的遗憾最大化自然甲骨文，这是一个非平稳的RL挑战。这种表述具有普遍的兴趣 - 我们通过与共同的评论家创建DDLPO的多代理扩展来解决RMAB。我们显示我们的方法在三个实验域中效果很好。