This study concerns the formulation and application of Bayesian optimal experimental design to symbolic discovery, which is the inference from observational data of predictive models taking general functional forms. We apply constrained first-order methods to optimize an appropriate selection criterion, using Hamiltonian Monte Carlo to sample from the prior. A step for computing the predictive distribution, involving convolution, is computed via either numerical integration, or via fast transform methods.
translated by 谷歌翻译
量子计算为某些问题提供了指数加速的潜力。但是,许多具有可证明加速的现有算法都需要当前不可用的耐故障量子计算机。我们提出了NISQ-TDA,这是第一个完全实现的量子机学习算法,其在任意经典(非手动)数据上具有可证明的指数加速,并且仅需要线性电路深度。我们报告了我们的NISQ-TDA算法的成功执行,该算法应用于在量子计算设备以及嘈杂的量子模拟器上运行的小数据集。我们从经验上证实,该算法对噪声是可靠的,并提供了目标深度和噪声水平,以实现现实世界中问题的近期,无耐受耐受性的量子优势。我们独特的数据加载投影方法是噪声鲁棒性的主要来源,引入了一种新的自我校正数据加载方法。
translated by 谷歌翻译
我们研究基于Krylov子空间的迭代方法,用于在任何Schatten $ p $ Norm中的低级别近似值。在这里,通过矩阵向量产品访问矩阵$ a $ $如此$ \ | a(i -zz^\ top)\ | _ {s_p} \ leq(1+ \ epsilon)\ min_ {u^\ top u = i_k} } $,其中$ \ | m \ | _ {s_p} $表示$ m $的单数值的$ \ ell_p $ norm。对于$ p = 2 $(frobenius norm)和$ p = \ infty $(频谱规范)的特殊情况,musco and Musco(Neurips 2015)获得了基于Krylov方法的算法,该方法使用$ \ tilde {o}(k)(k /\ sqrt {\ epsilon})$ matrix-vector产品,改进na \“ ive $ \ tilde {o}(k/\ epsilon)$依赖性,可以通过功率方法获得,其中$ \ tilde {o} $抑制均可抑制poly $(\ log(dk/\ epsilon))$。我们的主要结果是仅使用$ \ tilde {o}(kp^{1/6}/\ epsilon^{1/3} {1/3})$ matrix $ matrix的算法 - 矢量产品,并为所有$ p \ geq 1 $。为$ p = 2 $工作,我们的限制改进了先前的$ \ tilde {o}(k/\ epsilon^{1/2})$绑定到$ \ tilde {o}(k/\ epsilon^{1/3})$。由于schatten- $ p $和schatten-$ \ infty $ norms在$(1+ \ epsilon)$ pers $ p时相同\ geq(\ log d)/\ epsilon $,我们的界限恢复了Musco和Musco的结果,以$ p = \ infty $。此外,我们证明了矩阵矢量查询$ \ omega的下限(1/\ epsilon^ {1/3})$对于任何固定常数$ p \ geq 1 $,表明令人惊讶的$ \ tilde {\ theta}(1/\ epsilon^{ 1/3})$是常数〜$ k $的最佳复杂性。为了获得我们的结果,我们介绍了几种新技术,包括同时对多个Krylov子空间进行优化,以及针对分区操作员的不平等现象。我们在[1,2] $中以$ p \的限制使用了Araki-lieb-thirring Trace不平等,而对于$ p> 2 $,我们呼吁对安装分区操作员的规范压缩不平等。
translated by 谷歌翻译
在数值线性代数社区中,建议要获得诸如等级计算等各种问题的几乎最佳边界,找到最大线性独立的列(基础),回归或低秩近似,自然方式是解决尼尔森和尼文森的主要开放问题(Focs,2013)。该问题关于现有的忽略子空间嵌入的草图维度的对数因子,实现了恒因子近似的嵌入。我们展示了如何使用精细的草图技术绕过这个问题,并获得这些问题的最佳或几乎最佳的范围。我们使用的关键技术是基于不确定原理和提取器的Indyk的明确映射,在首次应用已知的漏窃子空间嵌入后,允许我们快速展开载体的质量,以便采样现在有效。由此,我们避免了在使用矩阵Chernoff不平等的界限中是标准的草图维度的对数因子。对于排名计算的基本问题和找到基础,我们的算法改善了张,郭和刘(Jacm,2013),并且在恒因因子和多个(日志日志(n)) - 因子中是最佳的。此外,对于恒定因子回归和低秩近似,我们给出了当前矩阵乘法指数的第一个最佳算法。
translated by 谷歌翻译
我们创建经典的(非量词)动态数据结构,为推荐系统和最小二乘回归的查询提供了与量子类似物相当的查询。近年来,这种算法的去量化引起了人们的关注。我们为这些问题获得了更清晰的界限。更重要的是,我们通过争辩说,这些问题的先前量子启发算法正在做杠杆或脊杠杆得分取样,以实现这些改进。这些是随机数值线性代数中强大而标准的技术。有了这种识别,我们能够在数值线性代数中采用大量工作来获得这些问题的算法,这些算法比现有方法更简单或更快(或两者兼而有之)。我们的实验表明,所提出的数据结构在现实世界数据集上也很好地工作。
translated by 谷歌翻译
长期以来,科学家一直旨在发现有意义的公式,以准确描述实验数据。一种常见的方法是使用域知识手动创建自然现象的数学模型,然后将这些模型拟合到数据。相比之下,机器学习算法在消耗大量数据的同时可以自动化准确的数据驱动模型的构建。在文献中探讨了对学习模型的功能形式(例如,非负)的逻辑约束的问题。但是,寻找与一般背景知识一致的模型是一个开放的问题。我们开发了一种将逻辑推理与符号回归相结合的方法,从而实现了自然现象模型的原则推导。我们演示了这些概念,用于开普勒的第三个行星运动定律,爱因斯坦的相对论时间稀释定律以及兰穆尔的吸附理论,在每种情况下都会将实验数据与背景理论自动连接起来。我们表明,使用形式的逻辑推理将正确的公式与一组合理公式区分开时,可以从几个数据点发现法律,这些公式在数据上具有相似的错误。推理与机器学习的结合提供了对自然现象的关键方面的可概括见解。我们设想,这种组合将使能够发现基本科学定律,并认为我们的工作是自动化科学方法的关键第一步。
translated by 谷歌翻译
While the brain connectivity network can inform the understanding and diagnosis of developmental dyslexia, its cause-effect relationships have not yet enough been examined. Employing electroencephalography signals and band-limited white noise stimulus at 4.8 Hz (prosodic-syllabic frequency), we measure the phase Granger causalities among channels to identify differences between dyslexic learners and controls, thereby proposing a method to calculate directional connectivity. As causal relationships run in both directions, we explore three scenarios, namely channels' activity as sources, as sinks, and in total. Our proposed method can be used for both classification and exploratory analysis. In all scenarios, we find confirmation of the established right-lateralized Theta sampling network anomaly, in line with the temporal sampling framework's assumption of oscillatory differences in the Theta and Gamma bands. Further, we show that this anomaly primarily occurs in the causal relationships of channels acting as sinks, where it is significantly more pronounced than when only total activity is observed. In the sink scenario, our classifier obtains 0.84 and 0.88 accuracy and 0.87 and 0.93 AUC for the Theta and Gamma bands, respectively.
translated by 谷歌翻译
There are multiple scales of abstraction from which we can describe the same image, depending on whether we are focusing on fine-grained details or a more global attribute of the image. In brain mapping, learning to automatically parse images to build representations of both small-scale features (e.g., the presence of cells or blood vessels) and global properties of an image (e.g., which brain region the image comes from) is a crucial and open challenge. However, most existing datasets and benchmarks for neuroanatomy consider only a single downstream task at a time. To bridge this gap, we introduce a new dataset, annotations, and multiple downstream tasks that provide diverse ways to readout information about brain structure and architecture from the same image. Our multi-task neuroimaging benchmark (MTNeuro) is built on volumetric, micrometer-resolution X-ray microtomography images spanning a large thalamocortical section of mouse brain, encompassing multiple cortical and subcortical regions. We generated a number of different prediction challenges and evaluated several supervised and self-supervised models for brain-region prediction and pixel-level semantic segmentation of microstructures. Our experiments not only highlight the rich heterogeneity of this dataset, but also provide insights into how self-supervised approaches can be used to learn representations that capture multiple attributes of a single image and perform well on a variety of downstream tasks. Datasets, code, and pre-trained baseline models are provided at: https://mtneuro.github.io/ .
translated by 谷歌翻译
The ability to convert reciprocating, i.e., alternating, actuation into rotary motion using linkages is hindered fundamentally by their poor torque transmission capability around kinematic singularity configurations. Here, we harness the elastic potential energy of a linear spring attached to the coupler link of four-bar mechanisms to manipulate force transmission around the kinematic singularities. We developed a theoretical model to explore the parameter space for proper force transmission in slider-crank and rocker-crank four-bar kinematics. Finally, we verified the proposed model and methodology by building and testing a macro-scale prototype of a slider-crank mechanism. We expect this approach to enable the development of small-scale rotary engines and robotic devices with closed kinematic chains dealing with serial kinematic singularities, such as linkages and parallel manipulators.
translated by 谷歌翻译
This paper considers a combination of actuation tendons and measurement strings to achieve accurate shape sensing and direct kinematics of continuum robots. Assuming general string routing, a methodical Lie group formulation for the shape sensing of these robots is presented. The shape kinematics is expressed using arc-length-dependent curvature distributions parameterized by modal functions, and the Magnus expansion for Lie group integration is used to express the shape as a product of exponentials. The tendon and string length kinematic constraints are solved for the modal coefficients and the configuration space and body Jacobian are derived. The noise amplification index for the shape reconstruction problem is defined and used for optimizing the string/tendon routing paths, and a planar simulation study shows the minimal number of strings/tendons needed for accurate shape reconstruction. A torsionally stiff continuum segment is used for experimental evaluation, demonstrating mean (maximal) end-effector absolute position error of less than 2% (5%) of total length. Finally, a simulation study of a torsionally compliant segment demonstrates the approach for general deflections and string routings. We believe that the methods of this paper can benefit the design process, sensing and control of continuum and soft robots.
translated by 谷歌翻译