我们重新审视了最简单的设置之一中的政策梯度方法的有限时间分析：有限状态和动作MDP，具有由所有随机策略组成的策略类和精确的渐变评估。有一些最近的工作将此设置视为平滑的非线性优化问题的实例，并显示具有小阶梯大小的子线性收敛速率。在这里，我们根据与政策迭代的连接采取不同的透视，并显示政策梯度方法的许多变体成功，阶梯大小大，并达到了线性收敛速率。

策略梯度方法适用于复杂的，不理解的，通过对参数化的策略进行随机梯度下降来控制问题。不幸的是，即使对于可以通过标准动态编程技术解决的简单控制问题，策略梯度算法也会面临非凸优化问题，并且被广泛理解为仅收敛到固定点。这项工作确定了结构属性 - 通过几个经典控制问题共享 - 确保策略梯度目标函数尽管是非凸面，但没有次优的固定点。当这些条件得到加强时，该目标满足了产生收敛速率的Polyak-lojasiewicz（梯度优势）条件。当其中一些条件放松时，我们还可以在任何固定点的最佳差距上提供界限。

Contrails, short for condensation trails, are line-shaped ice clouds produced by aircraft engine exhaust when they fly through cold and humid air. They generate a greenhouse effect by absorbing or directing back to Earth approximately 33% of emitted outgoing longwave radiation. They account for over half of the climate change resulting from aviation activities. Avoiding contrails and adjusting flight routes could be an inexpensive and effective way to reduce their impact. An accurate, automated, and reliable detection algorithm is required to develop and evaluate contrail avoidance strategies. Advancement in contrail detection has been severely limited due to several factors, primarily due to a lack of quality-labeled data. Recently, proposed a large human-labeled Landsat-8 contrails dataset. Each contrail is carefully labeled with various inputs in various scenes of Landsat-8 satellite imagery. In this work, we benchmark several popular segmentation models with combinations of different loss functions and encoder backbones. This work is the first to apply state-of-the-art segmentation techniques to detect contrails in low-orbit satellite imagery. Our work can also be used as an open benchmark for contrail segmentation and is publicly available.

The first large-scale deployment of private federated learning uses differentially private counting in the continual release model as a subroutine (Google AI blog titled "Federated Learning with Formal Differential Privacy Guarantees"). In this case, a concrete bound on the error is very relevant to reduce the privacy parameter. The standard mechanism for continual counting is the binary mechanism. We present a novel mechanism and show that its mean squared error is both asymptotically optimal and a factor 10 smaller than the error of the binary mechanism. We also show that the constants in our analysis are almost tight by giving non-asymptotic lower and upper bounds that differ only in the constants of lower-order terms. Our algorithm is a matrix mechanism for the counting matrix and takes constant time per release. We also use our explicit factorization of the counting matrix to give an upper bound on the excess risk of the private learning algorithm of Denisov et al. (NeurIPS 2022). Our lower bound for any continual counting mechanism is the first tight lower bound on continual counting under approximate differential privacy. It is achieved using a new lower bound on a certain factorization norm, denoted by $\gamma_F(\cdot)$, in terms of the singular values of the matrix. In particular, we show that for any complex matrix, $A \in \mathbb{C}^{m \times n}$, \[ \gamma_F(A) \geq \frac{1}{\sqrt{m}}\|A\|_1, \] where $\|\cdot \|$ denotes the Schatten-1 norm. We believe this technique will be useful in proving lower bounds for a larger class of linear queries. To illustrate the power of this technique, we show the first lower bound on the mean squared error for answering parity queries.

Deep Ensemble Convolutional Neural Networks has become a methodology of choice for analyzing medical images with a diagnostic performance comparable to a physician, including the diagnosis of Diabetic Retinopathy. However, commonly used techniques are deterministic and are therefore unable to provide any estimate of predictive uncertainty. Quantifying model uncertainty is crucial for reducing the risk of misdiagnosis. A reliable architecture should be well-calibrated to avoid over-confident predictions. To address this, we propose a UATTA-ENS: Uncertainty-Aware Test-Time Augmented Ensemble Technique for 5 Class PIRC Diabetic Retinopathy Classification to produce reliable and well-calibrated predictions.

全向视频中的光流估计面临两个重要问题：缺乏基准数据集以及调整基于视频的方法以适应全向性质的挑战。本文提出了第一个具有360度视野Flow360的感知上天然合成的全向基准数据集，其中有40个不同的视频和4,000个视频帧。我们在数据集和现有的光流数据集之间进行了全面的特征分析和比较，这些数据集表现出感知现实主义，独特性和多样性。为了适应全向性质，我们提出了一个新颖的暹罗表示学习框架（SLOF）。我们以对比度的方式训练我们的网络，并结合了对比度损失和光流损失的混合损失函数。广泛的实验验证了所提出的框架的有效性，并在最新方法中显示出40％的性能提高。我们的Flow360数据集和代码可在https://siamlof.github.io/上找到。

管理折扣促销活动（“ Markdown”）是经营电子商务业务的重要组成部分，这里的效率低下可能会严重阻碍零售商的盈利能力。解决此问题的传统方法在很大程度上取决于价格弹性建模。但是，价格弹性建模的部分信息性质，以及保护盈利能力的不可谈判的责任，意味着机器学习从业人员经常必须经过巨大的时间来定义衡量离线模型质量的策略。面对这一点，许多零售商依靠基于规则的方法，因此可以通过机器学习来捕获的盈利能力获得可观的收益。在本文中，我们介绍了两个新颖的端到端降价管理系统，以优化零售商旅程的不同阶段的赌注。第一个系统“ ITHAX”制定了无需估算的理性供应方定价策略，并且可以用作“冷启动”解决方案，以收集降价数据，同时保持收入控制。第二个系统“ Prosotheus”为价格弹性提供了一个完整的降价优化的框架。我们详细描述了特定的建模和验证程序，在我们的经验中，这对于建立在现实世界中稳健性能的系统至关重要。与我们经验丰富的运营团队在受控的在线测试中做出的决策相比，这两种降级系统都具有卓越的盈利能力，相对于手动策略，改善了86％（Promotheus）和79％（ITHAX）。这些系统已被部署以在ASOS.com上管理Markdown，并且可以在各种零售电子商务环境中进行价格优化的价格优化。

在本文中，我们重新审视了私人经验风险最小化（DP-erm）和差异私有随机凸优化（DP-SCO）的问题。我们表明，来自统计物理学（Langevin Exfusion（LD））的经过良好研究的连续时间算法同时为DP-SCO和DP-SCO提供了最佳的隐私/实用性权衡，$ \ epsilon $ -DP和$ $ \ epsilon $ -DP和$ （\ epsilon，\ delta）$ - dp均用于凸和强烈凸损失函数。我们为LD提供新的时间和尺寸独立统一稳定性，并使用我们为$ \ epsilon $ -DP提供相应的最佳超额人口风险保证。 $ \ epsilon $ -DP的DP-SCO保证的一个重要属性是，它们将非私人最佳界限匹配为$ \ epsilon \与\ infty $。在此过程中，我们提供了各种技术工具，这些工具可能引起独立的关注：i）在两个相邻数据集上运行损失功能时，一个新的r \'enyi Divergence绑定了LD，ii）最后一个过多的经验风险范围迭代LD，类似于Shamir和Zhang的嘈杂随机梯度下降（SGD）和iii）的LD，对LD进行了两期多余的风险分析，其中第一阶段是当扩散在任何合理意义上都没有在任何合理意义上融合到固定分布时，在第二阶段扩散已收敛到吉布斯分布的变体。我们的普遍性结果至关重要地依赖于LD的动力学。当它融合到固定分布时，我们获得了$ \ epsilon $ -DP的最佳界限。当它仅在很短的时间内运行$ \ propto 1/p $时，我们在$（\ epsilon，\ delta）$ -DP下获得最佳界限。在这里，$ p $是模型空间的维度。

We study fine-grained error bounds for differentially private algorithms for counting under continual observation. Our main insight is that the matrix mechanism when using lower-triangular matrices can be used in the continual observation model. More specifically, we give an explicit factorization for the counting matrix $M_\mathsf{count}$ and upper bound the error explicitly. We also give a fine-grained analysis, specifying the exact constant in the upper bound. Our analysis is based on upper and lower bounds of the {\em completely bounded norm} (cb-norm) of $M_\mathsf{count}$. Along the way, we improve the best-known bound of 28 years by Mathias (SIAM Journal on Matrix Analysis and Applications, 1993) on the cb-norm of $M_\mathsf{count}$ for a large range of the dimension of $M_\mathsf{count}$. Furthermore, we are the first to give concrete error bounds for various problems under continual observation such as binary counting, maintaining a histogram, releasing an approximately cut-preserving synthetic graph, many graph-based statistics, and substring and episode counting. Finally, we note that our result can be used to get a fine-grained error bound for non-interactive local learning {and the first lower bounds on the additive error for $(\epsilon,\delta)$-differentially-private counting under continual observation.} Subsequent to this work, Henzinger et al. (SODA2023) showed that our factorization also achieves fine-grained mean-squared error.

包括机器学习在内的计算分析方法对基因组学和医学领域具有重大影响。高通量基因表达分析方法，例如微阵列技术和RNA测序产生大量数据。传统上，统计方法用于基因表达数据的比较分析。但是，针对样品观察分类或发现特征基因的分类的更复杂的分析需要复杂的计算方法。在这篇综述中，我们编译了用于分析表达微阵列数据的各种统计和计算工具。即使在表达微阵列的背景下讨论了这些方法，也可以将它们应用于RNA测序和定量蛋白质组学数据集的分析。我们讨论缺失价值的类型以及其插补中通常采用的方法和方法。我们还讨论了数据归一化，特征选择和特征提取的方法。最后，详细描述了分类和类发现方法及其评估参数。我们认为，这项详细的审查将帮助用户根据预期结果选择适当的方法来预处理和分析其数据。