标准化流量(NF)是基于可能性的强大生成模型,能够在表达性和拖延性之间进行折衷,以模拟复杂的密度。现已建立的研究途径利用了最佳运输(OT),并寻找Monge地图,即源和目标分布之间的努力最小的模型。本文介绍了一种基于Brenier的极性分解定理的方法,该方法将任何受过训练的NF转换为更高效率的版本而不改变最终密度。我们通过学习源(高斯)分布的重新排列来最大程度地减少源和最终密度之间的OT成本。由于Euler的方程式,我们进一步限制了导致估计的Monge图的路径,将估计的Monge地图放在量化量的差异方程的空间中。所提出的方法导致几种现有模型的OT成本降低的平滑流动,而不会影响模型性能。
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即使在给定的物种中,单个大脑在解剖结构和功能组织中也有所不同。当试图从受试者组收集的神经影像数据中得出可概括的结论时,个体间的可变性是一个主要障碍。当前的共同注册程序依赖于有限的数据,从而导致非常粗糙的主体间比对。在这项工作中,我们提出了一种基于最佳运输的主体间比对的新方法,称为融合不平衡的Gromov Wasserstein(FUGW)。该方法根据其功能特征的相似性来对齐皮质表面,以响应各种刺激设置,同时惩罚了单个地形组织的大变形。我们证明了FUGW非常适合全脑车地标的对齐。不平衡的功能可以处理以下事实:功能区域的大小各不相同。我们的结果表明,FUGW的对准显着增加了独立功能数据的活动间相关性,并导致在组级别上更精确的映射。
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引入了Wasserstein距离的许多变体,以减轻其原始计算负担。尤其是切成薄片的距离(SW),该距离(SW)利用了一维投影,可以使用封闭式的瓦斯汀距离解决方案。然而,它仅限于生活在欧几里得空间中的数据,而Wasserstein距离已被研究和最近在歧管上使用。我们更具体地专门地关注球体,为此定义了新颖的SW差异,我们称之为球形切片 - 拖鞋,这是朝着定义SW差异的第一步。我们的构造明显基于圆圈上瓦斯汀距离的封闭式解决方案,以及新的球形ra径。除了有效的算法和相应的实现外,我们在几个机器学习用例中说明了它的属性,这些用例中,数据的球形表示受到威胁:在球体上的密度估计,变异推理或超球体自动编码器。
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比较图形等结构的对象是许多学习任务中涉及的基本操作。为此,基于最优传输(OT)的Gromov-Wasserstein(GW)距离已被证明可以成功处理相关对象的特定性质。更具体地说,通过节点连接关系,GW在图表上运行,视为特定空间上的概率测量。在OT的核心处是质量守恒的想法,这在两个被认为的图表中的所有节点之间施加了耦合。我们在本文中争辩说,这种财产可能对图形字典或分区学习等任务有害,我们通过提出新的半轻松的Gromov-Wasserstein发散来放松它。除了立即计算福利之外,我们讨论其属性,并表明它可以导致有效的图表字典学习算法。我们经验展示其对图形上的复杂任务的相关性,例如分区,聚类和完成。
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最佳运输(OT)理论下潜许多新兴机器学习(ML)方法现在解决了各种任务,例如生成建模,转移学习和信息检索。然而,这些后者通常会在传统的OT设置上具有两个分布,同时留下更一般的多边缘OT配方,稍微探索。在本文中,我们研究了多边缘OT(MMOT)问题,并通过促进关于耦合的结构信息,统一其伞下的几种流行的OT方法。我们表明将这种结构信息结合到MMOT中,在允许我们在数值上解决它的不同凸(DC)编程问题的实例。尽管后一级的计算成本高,但DC优化提供的解决方案通常与使用当前采用的优化方案获得的解决方案一样定性。
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Remote sensing satellites capture the cyclic dynamics of our Planet in regular time intervals recorded in satellite time series data. End-to-end trained deep learning models use this time series data to make predictions at a large scale, for instance, to produce up-to-date crop cover maps. Most time series classification approaches focus on the accuracy of predictions. However, the earliness of the prediction is also of great importance since coming to an early decision can make a crucial difference in time-sensitive applications. In this work, we present an End-to-End Learned Early Classification of Time Series (ELECTS) model that estimates a classification score and a probability of whether sufficient data has been observed to come to an early and still accurate decision. ELECTS is modular: any deep time series classification model can adopt the ELECTS conceptual idea by adding a second prediction head that outputs a probability of stopping the classification. The ELECTS loss function then optimizes the overall model on a balanced objective of earliness and accuracy. Our experiments on four crop classification datasets from Europe and Africa show that ELECTS allows reaching state-of-the-art accuracy while reducing the quantity of data massively to be downloaded, stored, and processed. The source code is available at https://github.com/marccoru/elects.
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This article formulates a generic representation of a path-following controller operating under contained motion, which was developed in the context of surgical robotics. It reports two types of constrained motion: i) Bilateral Constrained Motion, also called Remote Center Motion (RCM), and ii) Unilaterally Constrained Motion (UCM). In the first case, the incision hole has almost the same diameter as the robotic tool. In contrast, in the second state, the diameter of the incision orifice is larger than the tool diameter. The second case offers more space where the surgical instrument moves freely without constraints before touching the incision wall. The proposed method combines two tasks that must operate hierarchically: i) respect the RCM or UCM constraints formulated by equality or inequality, respectively, and ii) perform a surgical assignment, e.g., scanning or ablation expressed as a 3D path-following task. The proposed methods and materials were tested first on our simulator that mimics realistic conditions of middle ear surgery, and then on an experimental platform. Different validation scenarios were carried out experimentally to assess quantitatively and qualitatively each developed approach. Although ultimate precision was not the goal of this work, our concept is validated with enough accuracy (inferior to 100 micrometres) for ear surgery.
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Several self-supervised representation learning methods have been proposed for reinforcement learning (RL) with rich observations. For real-world applications of RL, recovering underlying latent states is crucial, particularly when sensory inputs contain irrelevant and exogenous information. In this work, we study how information bottlenecks can be used to construct latent states efficiently in the presence of task-irrelevant information. We propose architectures that utilize variational and discrete information bottlenecks, coined as RepDIB, to learn structured factorized representations. Exploiting the expressiveness bought by factorized representations, we introduce a simple, yet effective, bottleneck that can be integrated with any existing self-supervised objective for RL. We demonstrate this across several online and offline RL benchmarks, along with a real robot arm task, where we find that compressed representations with RepDIB can lead to strong performance improvements, as the learned bottlenecks help predict only the relevant state while ignoring irrelevant information.
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To face the dependency on fossil fuels and limit carbon emissions, fuel cells are a very promising technology and appear to be a key candidate to tackle the increase of the energy demand and promote the energy transition. To meet future needs for both transport and stationary applications, the time to market of fuel cell stacks must be drastically reduced. Here, a new concept to shorten their development time by introducing a disruptive and highefficiency data augmentation approach based on artificial intelligence is presented. Our results allow reducing the testing time before introducing a product on the market from a thousand to a few hours. The innovative concept proposed here can support engineering and research tasks during the fuel cell development process to achieve decreased development costs alongside a reduced time to market.
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A learned system uses machine learning (ML) internally to improve performance. We can expect such systems to be vulnerable to some adversarial-ML attacks. Often, the learned component is shared between mutually-distrusting users or processes, much like microarchitectural resources such as caches, potentially giving rise to highly-realistic attacker models. However, compared to attacks on other ML-based systems, attackers face a level of indirection as they cannot interact directly with the learned model. Additionally, the difference between the attack surface of learned and non-learned versions of the same system is often subtle. These factors obfuscate the de-facto risks that the incorporation of ML carries. We analyze the root causes of potentially-increased attack surface in learned systems and develop a framework for identifying vulnerabilities that stem from the use of ML. We apply our framework to a broad set of learned systems under active development. To empirically validate the many vulnerabilities surfaced by our framework, we choose 3 of them and implement and evaluate exploits against prominent learned-system instances. We show that the use of ML caused leakage of past queries in a database, enabled a poisoning attack that causes exponential memory blowup in an index structure and crashes it in seconds, and enabled index users to snoop on each others' key distributions by timing queries over their own keys. We find that adversarial ML is a universal threat against learned systems, point to open research gaps in our understanding of learned-systems security, and conclude by discussing mitigations, while noting that data leakage is inherent in systems whose learned component is shared between multiple parties.
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