根据线性随机微分方程进化的扩散过程是连续时间动态决策模型的重要家族。最佳政策对它们进行了充分研究,并确定了漂移矩阵。然而,对于不确定的漂移矩阵的扩散过程的数据驱动的控制知之甚少,因为常规离散时间分析技术不适用。此外,尽管该任务可以被视为涉及探索和剥削权衡取舍的强化学习问题,但确保系统稳定性是设计最佳政策的基本组成部分。我们确定流行的汤普森采样算法可以快速学习最佳动作,仅产生了时间根的遗憾,并在短时间内稳定了系统。据我们所知,这是汤普森在扩散过程控制问题中抽样的第一个结果。我们通过从两个飞机和血糖控制的两个设置的实际参数矩阵的经验模拟来验证理论结果。此外,我们观察到,与最先进的算法相比,汤普森采样显着改善(最坏的)遗憾,这表明汤普森采样以一种更加保护的方式探索。我们的理论分析涉及特定的特定最优歧管,该歧管将漂移参数的局部几何形状与扩散过程的最佳控制。我们希望这项技术具有更广泛的兴趣。
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这项工作研究了无处不在的强化学习政策的理论绩效保证,用于控制随机线性季节系统的规范模型。我们表明,随机确定性等效策略解决了探索 - 开发困境,以最大程度地减少根据随机微分方程进化的线性动力学系统中的二次成本。更确切地说,我们建立了时间段的正方形遗憾界限,表明随机确定性等效策略可以从单个状态轨迹中快速学习最佳控制动作。此外,显示了与参数数量的线性缩放。提出的分析介绍了新颖而有用的技术方法,并阐明了连续时间增强学习的基本挑战。
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基于学习的线性系统控制最近收到了大量的注意。在流行的设置中,真正的动态模型对决策者未知,并且需要通过将控制输入应用于系统来交互式学习。与用于自适应控制单个系统的有效加强学习政策的成熟文献不同,目前没有导致多个系统的联合学习的结果。特别是,快速可靠的关节稳定化的重要问题仍然是唯一的,因此这项工作的重点是唯一的。我们提出了一种新颖的基于联合学习的稳定算法,用于从不稳定状态轨迹的数据中快速地学习所有系统的稳定政策。所提出的程序被认为是显着有效的,使得它在极短的时间段内稳定动力系统系列。
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线性动力学系统是具有不确定动态的基于植物学习控制的规范模型。该设置包括一种随机微分方程,其捕获植物的状态演变,而真正的动态矩阵是未知的,并且需要从观察到的状态轨迹的数据学习。一个重要的问题是确保系统稳定,并且由于模型不确定性而稳定并使控制行动被排除在尽快。为此目的的可靠稳定过程可以有效地学习不稳定的数据,以在有限时间内稳定系统的不可用。在这项工作中,我们提出了一种新颖的贝叶斯学习算法,该算法稳定了未知的连续时间随机线性系统。呈现的算法是灵活的,并且在与系统相互作用的显着短时间后暴露有效的稳定性能。
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学习线性时间不变动态系统(LTID)的参数是当前兴趣的问题。在许多应用程序中,人们有兴趣联合学习多个相关LTID的参数,这仍然是未探究的日期。为此,我们开发一个联合估计器,用于学习共享常见基矩阵的LTID的过渡矩阵。此外,我们建立有限时间误差界限,取决于底层的样本大小,维度,任务数和转换矩阵的光谱属性。结果是在轻度规律假设下获得的,并在单独学习每个系统的比较中,展示从LTID的汇集信息汇总信息。我们还研究了错过过渡矩阵的联合结构的影响,并显示成立的结果在适度误操作的存在下是强大的。
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背景多武装匪徒是加强学习的经典模型,用于与个别信息相关联的顺序决策。用于匪徒的广泛使用的策略是汤普森采样,其中来自数据驱动的概率信念关于未知参数的样本用于选择控制动作。对于这种计算快速算法,性能分析可在完整的上下文中提供。然而,对于未完全观察到的问题,众所周知。我们提出了汤普森采样算法,用于部分可观察到的上下文多武装匪,并建立理论性能保证。从技术上讲,我们表明,所呈现的策略的遗憾与时间和臂的数量和尺寸线性缩放。此外,我们建立学习未知参数的速率,并提供说明性的数值分析。
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Climate change is expected to intensify and increase extreme events in the weather cycle. Since this has a significant impact on various sectors of our life, recent works are concerned with identifying and predicting such extreme events from Earth observations. This paper proposes a 2D/3D two-branch convolutional neural network (CNN) for wildfire danger forecasting. To use a unified framework, previous approaches duplicate static variables along the time dimension and neglect the intrinsic differences between static and dynamic variables. Furthermore, most existing multi-branch architectures lose the interconnections between the branches during the feature learning stage. To address these issues, we propose a two-branch architecture with a Location-aware Adaptive Denormalization layer (LOADE). Using LOADE as a building block, we can modulate the dynamic features conditional on their geographical location. Thus, our approach considers feature properties as a unified yet compound 2D/3D model. Besides, we propose using an absolute temporal encoding for time-related forecasting problems. Our experimental results show a better performance of our approach than other baselines on the challenging FireCube dataset.
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Prostate cancer (PCa) is one of the most prevalent cancers in men and many people around the world die from clinically significant PCa (csPCa). Early diagnosis of csPCa in bi-parametric MRI (bpMRI), which is non-invasive, cost-effective, and more efficient compared to multiparametric MRI (mpMRI), can contribute to precision care for PCa. The rapid rise in artificial intelligence (AI) algorithms are enabling unprecedented improvements in providing decision support systems that can aid in csPCa diagnosis and understanding. However, existing state of the art AI algorithms which are based on deep learning technology are often limited to 2D images that fails to capture inter-slice correlations in 3D volumetric images. The use of 3D convolutional neural networks (CNNs) partly overcomes this limitation, but it does not adapt to the anisotropy of images, resulting in sub-optimal semantic representation and poor generalization. Furthermore, due to the limitation of the amount of labelled data of bpMRI and the difficulty of labelling, existing CNNs are built on relatively small datasets, leading to a poor performance. To address the limitations identified above, we propose a new Zonal-aware Self-supervised Mesh Network (Z-SSMNet) that adaptatively fuses multiple 2D, 2.5D and 3D CNNs to effectively balance representation for sparse inter-slice information and dense intra-slice information in bpMRI. A self-supervised learning (SSL) technique is further introduced to pre-train our network using unlabelled data to learn the generalizable image features. Furthermore, we constrained our network to understand the zonal specific domain knowledge to improve the diagnosis precision of csPCa. Experiments on the PI-CAI Challenge dataset demonstrate our proposed method achieves better performance for csPCa detection and diagnosis in bpMRI.
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Information extraction from scholarly articles is a challenging task due to the sizable document length and implicit information hidden in text, figures, and citations. Scholarly information extraction has various applications in exploration, archival, and curation services for digital libraries and knowledge management systems. We present MORTY, an information extraction technique that creates structured summaries of text from scholarly articles. Our approach condenses the article's full-text to property-value pairs as a segmented text snippet called structured summary. We also present a sizable scholarly dataset combining structured summaries retrieved from a scholarly knowledge graph and corresponding publicly available scientific articles, which we openly publish as a resource for the research community. Our results show that structured summarization is a suitable approach for targeted information extraction that complements other commonly used methods such as question answering and named entity recognition.
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Measuring growth rates of apple fruitlets is important because it allows apple growers to determine when to apply chemical thinners to their crops to optimize yield. The current practice of obtaining growth rates involves using calipers to record sizes of fruitlets across multiple days. Due to the number of fruitlets needed to be sized, this method is laborious, time-consuming, and prone to human error. In this paper, we present a computer vision approach to measure the sizes and growth rates of apple fruitlets. With images collected by a hand-held stereo camera, our system detects, segments, and fits ellipses to fruitlets to measure their diameters. To measure growth rates, we utilize an Attentional Graph Neural Network to associate fruitlets across different days. We provide quantitative results on data collected in an apple orchard, and demonstrate that our system is able to predict abscise rates within 3% of the current method with a 7 times improvement in speed, while requiring significantly less manual effort. Moreover, we provide results on images captured by a robotic system in the field, and discuss the next steps to make the process fully autonomous.
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