时空时间序列的神经预测推动了几个相关应用领域的研究和工业创新。图神经网络（GNN）通常是预测体系结构的核心组成部分。但是，在大多数时空gnns中，计算复杂度比序列时间长度缩放到二次因子，图中链接的数量是图中的链接数，因此阻碍了这些模型在大图和长时间序列中的应用。尽管在静态图的背景下提出了提高可伸缩性的方法，但很少有研究工作专门用于时空情况。为了填补这一空白，我们提出了一个可扩展的体系结构，该体系结构利用了时间和空间动力学的有效编码。特别是，我们使用一个随机的复发神经网络将输入时间序列的历史嵌入到包括多尺度时间动力学的高维状态表示中。然后，使用图形邻接矩阵的不同功率沿空间维度沿空间维度传播，以生成以富含时空特征池的特征的节点嵌入。可以在不监督的方式中有效地预先计算所得的节点嵌入，然后将其馈送到馈送前向解码器，该解码器学会映射多尺度时空表示形式为预测。然后，可以通过对节点的嵌入而无需破坏任何依赖性，从而使训练过程在节点方面并行化，从而可以对大型网络进行可扩展性。相关数据集的经验结果表明，我们的方法可以与最新技术的状态竞争，同时大大减轻了计算负担。

Outstanding achievements of graph neural networks for spatiotemporal time series analysis show that relational constraints introduce an effective inductive bias into neural forecasting architectures. Often, however, the relational information characterizing the underlying data-generating process is unavailable and the practitioner is left with the problem of inferring from data which relational graph to use in the subsequent processing stages. We propose novel, principled - yet practical - probabilistic score-based methods that learn the relational dependencies as distributions over graphs while maximizing end-to-end the performance at task. The proposed graph learning framework is based on consolidated variance reduction techniques for Monte Carlo score-based gradient estimation, is theoretically grounded, and, as we show, effective in practice. In this paper, we focus on the time series forecasting problem and show that, by tailoring the gradient estimators to the graph learning problem, we are able to achieve state-of-the-art performance while controlling the sparsity of the learned graph and the computational scalability. We empirically assess the effectiveness of the proposed method on synthetic and real-world benchmarks, showing that the proposed solution can be used as a stand-alone graph identification procedure as well as a graph learning component of an end-to-end forecasting architecture.

高吞吐量数据处理应用的高效硬件加速器设计，例如深度神经网络，是计算机架构设计中有挑战性的任务。在这方面，高级合成（HLS）作为快速原型设计的解决方案，从应用程序计算流程的行为描述开始。这种设计空间探索（DSE）旨在识别帕累托最佳的合成配置，其穷举搜索由于设计空间维度和合成过程的禁止计算成本而往往不可行。在该框架内，我们通过提出在文献中，有效和有效地解决了设计问题图形神经网络，该神经网络共同预测了合成的行为规范的加速性能和硬件成本给出了优化指令。考虑到性能和成本估计，学习模型可用于通过引导DSE来快速接近帕累托曲线。所提出的方法优于传统的HLS驱动DSE方法，通过考虑任意长度的计算机程序和输入的不变特性。我们提出了一种新颖的混合控制和数据流图表示，可以在不同硬件加速器的规格上培训图形神经网络;该方法自然地转移到解除数据处理应用程序。此外，我们表明我们的方法实现了与常用模拟器的预测准确性相当，而无需访问HLS编译器和目标FPGA的分析模型，同时是更快的数量级。最后，通过微调来自新目标域的少量样本，可以在未开发的配置空间中解放所学习的表示。

基于Q学习的强化学习算法正在推动深入的强化学习（DRL）研究，以解决复杂的问题并在其中许多方面实现超人的表现。然而，已知Q学习是积极偏见的，因为它通过使用最大值的期望值噪声估计来学习。对动作值的系统高估与DRL方法的固有较高方差相结合会导致逐渐积累的错误，从而导致学习算法的差异。理想情况下，我们希望DRL代理人考虑到他们对每个动作的最佳性的不确定性，并能够利用它以对预期收益进行更明智的估计。在这方面，加权Q学习（WQL）有效地减少了偏见，并在随机环境中显示出显着的结果。 WQL使用估计动作值的加权总和，其中权重对应于每个动作值的概率为最大值。但是，这些概率的计算仅在表格设置中是实用的。在这项工作中，我们通过使用接受辍学训练的神经网络作为深豪斯过程的有效近似，从而提供了方法上的进步，以从DRL中的WQL属性中受益。特别是，我们采用具体的辍学变体来获得DRL认知不确定性的校准估计值。然后，通过采取几个随机前向通过动作值网络并以蒙特卡洛的方式计算权重来获得估计器。这样的权重是对应于最大W.R.T.的每个动作值的概率的贝叶斯估计。通过辍学估计的后验概率分布。我们展示了我们的新颖加权Q学习算法如何减少偏见W.R.T.相关基线，并提供了其在代表性基准方面的优势的经验证据。

Computational units in artificial neural networks follow a simplified model of biological neurons. In the biological model, the output signal of a neuron runs down the axon, splits following the many branches at its end, and passes identically to all the downward neurons of the network. Each of the downward neurons will use their copy of this signal as one of many inputs dendrites, integrate them all and fire an output, if above some threshold. In the artificial neural network, this translates to the fact that the nonlinear filtering of the signal is performed in the upward neuron, meaning that in practice the same activation is shared between all the downward neurons that use that signal as their input. Dendrites thus play a passive role. We propose a slightly more complex model for the biological neuron, where dendrites play an active role: the activation in the output of the upward neuron becomes optional, and instead the signals going through each dendrite undergo independent nonlinear filterings, before the linear combination. We implement this new model into a ReLU computational unit and discuss its biological plausibility. We compare this new computational unit with the standard one and describe it from a geometrical point of view. We provide a Keras implementation of this unit into fully connected and convolutional layers and estimate their FLOPs and weights change. We then use these layers in ResNet architectures on CIFAR-10, CIFAR-100, Imagenette, and Imagewoof, obtaining performance improvements over standard ResNets up to 1.73%. Finally, we prove a universal representation theorem for continuous functions on compact sets and show that this new unit has more representational power than its standard counterpart.

Humans have internal models of robots (like their physical capabilities), the world (like what will happen next), and their tasks (like a preferred goal). However, human internal models are not always perfect: for example, it is easy to underestimate a robot's inertia. Nevertheless, these models change and improve over time as humans gather more experience. Interestingly, robot actions influence what this experience is, and therefore influence how people's internal models change. In this work we take a step towards enabling robots to understand the influence they have, leverage it to better assist people, and help human models more quickly align with reality. Our key idea is to model the human's learning as a nonlinear dynamical system which evolves the human's internal model given new observations. We formulate a novel optimization problem to infer the human's learning dynamics from demonstrations that naturally exhibit human learning. We then formalize how robots can influence human learning by embedding the human's learning dynamics model into the robot planning problem. Although our formulations provide concrete problem statements, they are intractable to solve in full generality. We contribute an approximation that sacrifices the complexity of the human internal models we can represent, but enables robots to learn the nonlinear dynamics of these internal models. We evaluate our inference and planning methods in a suite of simulated environments and an in-person user study, where a 7DOF robotic arm teaches participants to be better teleoperators. While influencing human learning remains an open problem, our results demonstrate that this influence is possible and can be helpful in real human-robot interaction.

Explainability is a vibrant research topic in the artificial intelligence community, with growing interest across methods and domains. Much has been written about the topic, yet explainability still lacks shared terminology and a framework capable of providing structural soundness to explanations. In our work, we address these issues by proposing a novel definition of explanation that is a synthesis of what can be found in the literature. We recognize that explanations are not atomic but the product of evidence stemming from the model and its input-output and the human interpretation of this evidence. Furthermore, we fit explanations into the properties of faithfulness (i.e., the explanation being a true description of the model's decision-making) and plausibility (i.e., how much the explanation looks convincing to the user). Using our proposed theoretical framework simplifies how these properties are ope rationalized and provide new insight into common explanation methods that we analyze as case studies.

Fruit is a key crop in worldwide agriculture feeding millions of people. The standard supply chain of fruit products involves quality checks to guarantee freshness, taste, and, most of all, safety. An important factor that determines fruit quality is its stage of ripening. This is usually manually classified by experts in the field, which makes it a labor-intensive and error-prone process. Thus, there is an arising need for automation in the process of fruit ripeness classification. Many automatic methods have been proposed that employ a variety of feature descriptors for the food item to be graded. Machine learning and deep learning techniques dominate the top-performing methods. Furthermore, deep learning can operate on raw data and thus relieve the users from having to compute complex engineered features, which are often crop-specific. In this survey, we review the latest methods proposed in the literature to automatize fruit ripeness classification, highlighting the most common feature descriptors they operate on.

Graph Neural Networks (GNNs) achieve state-of-the-art performance on graph-structured data across numerous domains. Their underlying ability to represent nodes as summaries of their vicinities has proven effective for homophilous graphs in particular, in which same-type nodes tend to connect. On heterophilous graphs, in which different-type nodes are likely connected, GNNs perform less consistently, as neighborhood information might be less representative or even misleading. On the other hand, GNN performance is not inferior on all heterophilous graphs, and there is a lack of understanding of what other graph properties affect GNN performance. In this work, we highlight the limitations of the widely used homophily ratio and the recent Cross-Class Neighborhood Similarity (CCNS) metric in estimating GNN performance. To overcome these limitations, we introduce 2-hop Neighbor Class Similarity (2NCS), a new quantitative graph structural property that correlates with GNN performance more strongly and consistently than alternative metrics. 2NCS considers two-hop neighborhoods as a theoretically derived consequence of the two-step label propagation process governing GCN's training-inference process. Experiments on one synthetic and eight real-world graph datasets confirm consistent improvements over existing metrics in estimating the accuracy of GCN- and GAT-based architectures on the node classification task.

In recent years, reinforcement learning (RL) has become increasingly successful in its application to science and the process of scientific discovery in general. However, while RL algorithms learn to solve increasingly complex problems, interpreting the solutions they provide becomes ever more challenging. In this work, we gain insights into an RL agent's learned behavior through a post-hoc analysis based on sequence mining and clustering. Specifically, frequent and compact subroutines, used by the agent to solve a given task, are distilled as gadgets and then grouped by various metrics. This process of gadget discovery develops in three stages: First, we use an RL agent to generate data, then, we employ a mining algorithm to extract gadgets and finally, the obtained gadgets are grouped by a density-based clustering algorithm. We demonstrate our method by applying it to two quantum-inspired RL environments. First, we consider simulated quantum optics experiments for the design of high-dimensional multipartite entangled states where the algorithm finds gadgets that correspond to modern interferometer setups. Second, we consider a circuit-based quantum computing environment where the algorithm discovers various gadgets for quantum information processing, such as quantum teleportation. This approach for analyzing the policy of a learned agent is agent and environment agnostic and can yield interesting insights into any agent's policy.