COVID-19的传播表明，在不同的城市和社区之间，传播风险模式不是同质的，各种异质特征会影响传播轨迹。因此，对于预测性大流行监测，至关重要的是，在城市和社区中探索潜在的异质特征，以区分其特定的大流行扩散轨迹。为此，这项研究创建了一个网络嵌入模型，捕获跨县的访问网络以及异质特征，以根据其大流行传播轨迹来发现美国县的集群。我们从3月3日至2020年6月29日（初始波浪）收集了2,787个县的位置智能特征。其次，我们构建了一个人类访问网络，该网络将县特征作为节点属性和县之间的访问作为网络边缘。我们的归因网络嵌入方法整合了跨县访问网络的类型学特征以及异质性特征。我们对属性网络嵌入进行了聚类分析，以揭示与四个县群相对应的差异风险轨迹的四种原型。随后，我们确定了四个功能是原型之间独特的传输风险模式的重要特征。归因的网络嵌入方法和发现识别并解释了整个县的非殖民性大流行风险轨迹进行预测性大流行监测。这项研究还为大流行分析的基于数据驱动和深度学习的方法有助于补充大流行病政策分析的标准流行病学模型。

尽管图形神经网络（GNNS）的巨大成功应用，但对其泛化能力的理论认识，特别是对于数据不是独立且相同分布的节点级任务（IID），稀疏。概括性绩效的理论调查有利于了解GNN模型的基本问题（如公平性）和设计更好的学习方法。在本文中，我们在非IID半监督学习设置下为GNN提供了一种新的PAC-Bayesian分析。此外，我们分析了未标记节点的不同子组上的泛化性能，这使我们能够通过理论观点进一步研究GNN的准确性 - （DIS）奇偶校准风格（UN）公平。在合理的假设下，我们证明了测试子组和训练集之间的距离可以是影响该子组上GNN性能的关键因素，这调用了对公平学习的培训节点选择。多个GNN模型和数据集的实验支持我们的理论结果。

Current mainstream object detection methods for large aerial images usually divide large images into patches and then exhaustively detect the objects of interest on all patches, no matter whether there exist objects or not. This paradigm, although effective, is inefficient because the detectors have to go through all patches, severely hindering the inference speed. This paper presents an Objectness Activation Network (OAN) to help detectors focus on fewer patches but achieve more efficient inference and more accurate results, enabling a simple and effective solution to object detection in large images. In brief, OAN is a light fully-convolutional network for judging whether each patch contains objects or not, which can be easily integrated into many object detectors and jointly trained with them end-to-end. We extensively evaluate our OAN with five advanced detectors. Using OAN, all five detectors acquire more than 30.0% speed-up on three large-scale aerial image datasets, meanwhile with consistent accuracy improvements. On extremely large Gaofen-2 images (29200$\times$27620 pixels), our OAN improves the detection speed by 70.5%. Moreover, we extend our OAN to driving-scene object detection and 4K video object detection, boosting the detection speed by 112.1% and 75.0%, respectively, without sacrificing the accuracy. Code is available at https://github.com/Ranchosky/OAN.

Graph Neural Networks(GNNs) are a family of neural models tailored for graph-structure data and have shown superior performance in learning representations for graph-structured data. However, training GNNs on large graphs remains challenging and a promising direction is distributed GNN training, which is to partition the input graph and distribute the workload across multiple machines. The key bottleneck of the existing distributed GNNs training framework is the across-machine communication induced by the dependency on the graph data and aggregation operator of GNNs. In this paper, we study the communication complexity during distributed GNNs training and propose a simple lossless communication reduction method, termed the Aggregation before Communication (ABC) method. ABC method exploits the permutation-invariant property of the GNNs layer and leads to a paradigm where vertex-cut is proved to admit a superior communication performance than the currently popular paradigm (edge-cut). In addition, we show that the new partition paradigm is particularly ideal in the case of dynamic graphs where it is infeasible to control the edge placement due to the unknown stochastic of the graph-changing process.

Hashing has been widely researched to solve the large-scale approximate nearest neighbor search problem owing to its time and storage superiority. In recent years, a number of online hashing methods have emerged, which can update the hash functions to adapt to the new stream data and realize dynamic retrieval. However, existing online hashing methods are required to update the whole database with the latest hash functions when a query arrives, which leads to low retrieval efficiency with the continuous increase of the stream data. On the other hand, these methods ignore the supervision relationship among the examples, especially in the multi-label case. In this paper, we propose a novel Fast Online Hashing (FOH) method which only updates the binary codes of a small part of the database. To be specific, we first build a query pool in which the nearest neighbors of each central point are recorded. When a new query arrives, only the binary codes of the corresponding potential neighbors are updated. In addition, we create a similarity matrix which takes the multi-label supervision information into account and bring in the multi-label projection loss to further preserve the similarity among the multi-label data. The experimental results on two common benchmarks show that the proposed FOH can achieve dramatic superiority on query time up to 6.28 seconds less than state-of-the-art baselines with competitive retrieval accuracy.

Multi-task learning (MTL) models have demonstrated impressive results in computer vision, natural language processing, and recommender systems. Even though many approaches have been proposed, how well these approaches balance different tasks on each parameter still remains unclear. In this paper, we propose to measure the task dominance degree of a parameter by the total updates of each task on this parameter. Specifically, we compute the total updates by the exponentially decaying Average of the squared Updates (AU) on a parameter from the corresponding task.Based on this novel metric, we observe that many parameters in existing MTL methods, especially those in the higher shared layers, are still dominated by one or several tasks. The dominance of AU is mainly due to the dominance of accumulative gradients from one or several tasks. Motivated by this, we propose a Task-wise Adaptive learning rate approach, AdaTask in short, to separate the \emph{accumulative gradients} and hence the learning rate of each task for each parameter in adaptive learning rate approaches (e.g., AdaGrad, RMSProp, and Adam). Comprehensive experiments on computer vision and recommender system MTL datasets demonstrate that AdaTask significantly improves the performance of dominated tasks, resulting SOTA average task-wise performance. Analysis on both synthetic and real-world datasets shows AdaTask balance parameters in every shared layer well.

Point cloud completion, as the upstream procedure of 3D recognition and segmentation, has become an essential part of many tasks such as navigation and scene understanding. While various point cloud completion models have demonstrated their powerful capabilities, their robustness against adversarial attacks, which have been proven to be fatally malicious towards deep neural networks, remains unknown. In addition, existing attack approaches towards point cloud classifiers cannot be applied to the completion models due to different output forms and attack purposes. In order to evaluate the robustness of the completion models, we propose PointCA, the first adversarial attack against 3D point cloud completion models. PointCA can generate adversarial point clouds that maintain high similarity with the original ones, while being completed as another object with totally different semantic information. Specifically, we minimize the representation discrepancy between the adversarial example and the target point set to jointly explore the adversarial point clouds in the geometry space and the feature space. Furthermore, to launch a stealthier attack, we innovatively employ the neighbourhood density information to tailor the perturbation constraint, leading to geometry-aware and distribution-adaptive modifications for each point. Extensive experiments against different premier point cloud completion networks show that PointCA can cause a performance degradation from 77.9% to 16.7%, with the structure chamfer distance kept below 0.01. We conclude that existing completion models are severely vulnerable to adversarial examples, and state-of-the-art defenses for point cloud classification will be partially invalid when applied to incomplete and uneven point cloud data.

Dialogue state tracking (DST) aims to convert the dialogue history into dialogue states which consist of slot-value pairs. As condensed structural information memorizing all history information, the dialogue state in the last turn is typically adopted as the input for predicting the current state by DST models. However, these models tend to keep the predicted slot values unchanged, which is defined as state momentum in this paper. Specifically, the models struggle to update slot values that need to be changed and correct wrongly predicted slot values in the last turn. To this end, we propose MoNET to tackle state momentum via noise-enhanced training. First, the previous state of each turn in the training data is noised via replacing some of its slot values. Then, the noised previous state is used as the input to learn to predict the current state, improving the model's ability to update and correct slot values. Furthermore, a contrastive context matching framework is designed to narrow the representation distance between a state and its corresponding noised variant, which reduces the impact of noised state and makes the model better understand the dialogue history. Experimental results on MultiWOZ datasets show that MoNET outperforms previous DST methods. Ablations and analysis verify the effectiveness of MoNET in alleviating state momentum and improving anti-noise ability.

视频和文本之间的跨模式检索因网络上的视频迅速出现而越来越多。通常，视频包含丰富的实例和事件信息，查询文本仅描述了信息的一部分。因此，视频可以对应于多个不同的文本说明和查询。我们将此现象称为``视频文本对应歧义''问题。当前技术主要集中于挖掘视频和文本内容之间的本地或多级对齐（\ textit {e.g。}，对实体和动词的动作对象）。这些方法很难通过仅使用一个单个功能来描述视频来减轻视频文本的歧义，这需要同时与多个不同的文本功能匹配。为了解决这个问题，我们提出了一个文本自适应多个视觉原型匹配模型，该模型会自动捕获多个原型，以通过自适应聚合视频令牌功能来描述视频。给定查询文本，相似性由最相似的原型确定，以在视频中找到对应关系，该视频称为文本自适应匹配。为了学习代表视频中丰富信息的多种原型，我们提出了差异损失，以鼓励不同的原型参与视频的不同内容。我们的方法在四个公共视频检索数据集上优于最先进的方法。

我们研究了可靠的功能表示的任务，旨在在多个数据集上良好地概括以进行行动识别。我们建立了有关变形金刚的功效的方法。尽管在过去的十年中，我们目睹了视频动作识别的巨大进展，但如何培训单个模型可以在多个数据集中表现良好的单一模型仍然充满挑战而有价值。在这里，我们提出了一种新颖的多数据集训练范式，Multitrain，设计了两个新的损失条款，即信息丰富的损失和投射损失，旨在学习稳健的表现以进行行动识别。特别是，信息性损失最大化了功能嵌入的表现力，而每个数据集的投影损失遍历了数据集的类之间的内在关系。我们验证方法对五个具有挑战性的数据集的有效性，即动力学400，动力学700，矩矩，活动网络和某种效果 - v2数据集。广泛的实验结果表明，我们的方法可以始终如一地提高最新性能。