Non-Pharmaceutical Interventions (NPIs), such as social gathering restrictions, have shown effectiveness to slow the transmission of COVID-19 by reducing the contact of people. To support policy-makers, multiple studies have first modeled human mobility via macro indicators (e.g., average daily travel distance) and then studied the effectiveness of NPIs. In this work, we focus on mobility modeling and, from a micro perspective, aim to predict locations that will be visited by COVID-19 cases. Since NPIs generally cause economic and societal loss, such a micro perspective prediction benefits governments when they design and evaluate them. However, in real-world situations, strict privacy data protection regulations result in severe data sparsity problems (i.e., limited case and location information). To address these challenges, we formulate the micro perspective mobility modeling into computing the relevance score between a diffusion and a location, conditional on a geometric graph. we propose a model named Deep Graph Diffusion Infomax (DGDI), which jointly models variables including a geometric graph, a set of diffusions and a set of locations.To facilitate the research of COVID-19 prediction, we present two benchmarks that contain geometric graphs and location histories of COVID-19 cases. Extensive experiments on the two benchmarks show that DGDI significantly outperforms other competing methods.

Contrastive learning methods based on InfoNCE loss are popular in node representation learning tasks on graph-structured data. However, its reliance on data augmentation and its quadratic computational complexity might lead to inconsistency and inefficiency problems. To mitigate these limitations, in this paper, we introduce a simple yet effective contrastive model named Localized Graph Contrastive Learning (Local-GCL in short). Local-GCL consists of two key designs: 1) We fabricate the positive examples for each node directly using its first-order neighbors, which frees our method from the reliance on carefully-designed graph augmentations; 2) To improve the efficiency of contrastive learning on graphs, we devise a kernelized contrastive loss, which could be approximately computed in linear time and space complexity with respect to the graph size. We provide theoretical analysis to justify the effectiveness and rationality of the proposed methods. Experiments on various datasets with different scales and properties demonstrate that in spite of its simplicity, Local-GCL achieves quite competitive performance in self-supervised node representation learning tasks on graphs with various scales and properties.

道路网络和轨迹表示学习对于交通系统至关重要，因为学习的表示形式可以直接用于各种下游任务（例如，交通速度推理和旅行时间估计）。但是，大多数现有方法仅在同一规模内对比，即分别处理道路网络和轨迹，这些方法忽略了有价值的相互关系。在本文中，我们旨在提出一个统一的框架，该框架共同学习道路网络和轨迹表示端到端。我们为公路对比度和轨迹 - 轨迹对比度分别设计了特定领域的增强功能，即路段及其上下文邻居和轨迹分别替换和丢弃了替代方案。最重要的是，我们进一步引入了路面跨尺度对比，与最大化总互信息桥接了这两个尺度。与仅在形成对比的图形及其归属节点上的现有跨尺度对比度学习方法不同，路段和轨迹之间的对比是通过新颖的正面抽样和适应性加权策略精心量身定制的。我们基于两个实际数据集进行了审慎的实验，这些数据集具有四个下游任务，证明了性能和有效性的提高。该代码可在https://github.com/mzy94/jclrnt上找到。

Recently, contrastive learning (CL) has emerged as a successful method for unsupervised graph representation learning. Most graph CL methods first perform stochastic augmentation on the input graph to obtain two graph views and maximize the agreement of representations in the two views. Despite the prosperous development of graph CL methods, the design of graph augmentation schemes-a crucial component in CL-remains rarely explored. We argue that the data augmentation schemes should preserve intrinsic structures and attributes of graphs, which will force the model to learn representations that are insensitive to perturbation on unimportant nodes and edges. However, most existing methods adopt uniform data augmentation schemes, like uniformly dropping edges and uniformly shuffling features, leading to suboptimal performance. In this paper, we propose a novel graph contrastive representation learning method with adaptive augmentation that incorporates various priors for topological and semantic aspects of the graph. Specifically, on the topology level, we design augmentation schemes based on node centrality measures to highlight important connective structures. On the node attribute level, we corrupt node features by adding more noise to unimportant node features, to enforce the model to recognize underlying semantic information. We perform extensive experiments of node classification on a variety of real-world datasets. Experimental results demonstrate that our proposed method consistently outperforms existing state-of-the-art baselines and even surpasses some supervised counterparts, which validates the effectiveness of the proposed contrastive framework with adaptive augmentation. CCS CONCEPTS• Computing methodologies → Unsupervised learning; Neural networks; Learning latent representations.

在线社交平台，例如Twitter，Facebook，LinkedIn和微信在过去十年中的发展非常快，并且是人们互相交流和共享信息的最有效平台之一。由于“口口相传”的效果，信息通常可以在这些社交媒体平台上迅速传播。因此，重要的是研究推动信息扩散的机制并量化信息传播的后果。许多努力都集中在这个问题上，以帮助我们更好地理解并在病毒营销和广告中实现更高的性能。另一方面，在过去的几年中，神经网络的发展蓬勃发展，导致大量的图表学习（GRL）模型。与传统模型相比，GRL方法通常被证明更有效。在本文中，我们对现有作品进行了全面的审查，该综述使用GRL方法用于普及预测问题，并根据其主要使用的模型和技术将相关文献分为两个大类：基于嵌入的方法和深度学习方法。深度学习方法进一步分为六个小类：卷积神经网络，图形卷积网络，图形注意力网络，图形神经网络，复发性神经网络和增强学习。我们比较这些不同模型的性能，并讨论它们的优势和局限性。最后，我们概述了受欢迎程度预测问题的挑战和未来机会。

Deep learning has been shown to be successful in a number of domains, ranging from acoustics, images, to natural language processing. However, applying deep learning to the ubiquitous graph data is non-trivial because of the unique characteristics of graphs. Recently, substantial research efforts have been devoted to applying deep learning methods to graphs, resulting in beneficial advances in graph analysis techniques. In this survey, we comprehensively review the different types of deep learning methods on graphs. We divide the existing methods into five categories based on their model architectures and training strategies: graph recurrent neural networks, graph convolutional networks, graph autoencoders, graph reinforcement learning, and graph adversarial methods. We then provide a comprehensive overview of these methods in a systematic manner mainly by following their development history. We also analyze the differences and compositions of different methods. Finally, we briefly outline the applications in which they have been used and discuss potential future research directions.

最近，最大化的互信息是一种强大的无监测图表表示学习的方法。现有方法通常有效地从拓扑视图中捕获信息但忽略特征视图。为了规避这个问题，我们通过利用功能和拓扑视图利用互信息最大化提出了一种新的方法。具体地，我们首先利用多视图表示学习模块来更好地捕获跨图形上的特征和拓扑视图的本地和全局信息内容。为了模拟由特征和拓扑空间共享的信息，我们使用相互信息最大化和重建损耗最小化开发公共表示学习模块。要明确鼓励图形表示之间的多样性在相同的视图中，我们还引入了一个分歧正则化，以扩大同一视图之间的表示之间的距离。合成和实际数据集的实验证明了集成功能和拓扑视图的有效性。特别是，与先前的监督方法相比，我们所提出的方法可以在无监督的代表和线性评估协议下实现可比或甚至更好的性能。

预测抗流动过程中感染的数量对政府制定抗流动策略极为有益，尤其是在细粒度的地理单位中。以前的工作着重于低空间分辨率预测，例如县级和预处理数据到同一地理水平，这将失去一些有用的信息。在本文中，我们提出了一个基于两个地理水平的数据，用于社区级别的COVID-19预测，该模型（FGC-COVID）基于数据。我们使用比社区更细粒度的地理水平（CBG）之间的人口流动数据来构建图形，并使用图形神经网络（GNN）构建图形并捕获CBG之间的依赖关系。为了预测，为了预测更细粒度的模式，引入了空间加权聚合模块，以将CBG的嵌入基于其地理隶属关系和空间自相关，将CBG的嵌入到社区水平上。在300天LA COVID-19数据中进行的大量实验表明，我们的模型的表现优于社区级Covid-19预测的现有预测模型。

Deep learning has revolutionized many machine learning tasks in recent years, ranging from image classification and video processing to speech recognition and natural language understanding. The data in these tasks are typically represented in the Euclidean space. However, there is an increasing number of applications where data are generated from non-Euclidean domains and are represented as graphs with complex relationships and interdependency between objects. The complexity of graph data has imposed significant challenges on existing machine learning algorithms. Recently, many studies on extending deep learning approaches for graph data have emerged. In this survey, we provide a comprehensive overview of graph neural networks (GNNs) in data mining and machine learning fields. We propose a new taxonomy to divide the state-of-the-art graph neural networks into four categories, namely recurrent graph neural networks, convolutional graph neural networks, graph autoencoders, and spatial-temporal graph neural networks. We further discuss the applications of graph neural networks across various domains and summarize the open source codes, benchmark data sets, and model evaluation of graph neural networks. Finally, we propose potential research directions in this rapidly growing field.

We introduce a self-supervised approach for learning node and graph level representations by contrasting structural views of graphs. We show that unlike visual representation learning, increasing the number of views to more than two or contrasting multi-scale encodings do not improve performance, and the best performance is achieved by contrasting encodings from first-order neighbors and a graph diffusion. We achieve new state-ofthe-art results in self-supervised learning on 8 out of 8 node and graph classification benchmarks under the linear evaluation protocol. For example, on Cora (node) and Reddit-Binary (graph) classification benchmarks, we achieve 86.8% and 84.5% accuracy, which are 5.5% and 2.4% relative improvements over previous state-of-the-art. When compared to supervised baselines, our approach outperforms them in 4 out of 8 benchmarks.

流行预测是有效控制流行病的关键，并帮助世界缓解威胁公共卫生的危机。为了更好地了解流行病的传播和演变，我们提出了Epignn，这是一种基于图神经网络的流行病预测模型。具体而言，我们设计了一个传输风险编码模块，以表征区域在流行过程中的局部和全局空间效应，并将其纳入模型。同时，我们开发了一个区域感知的图形学习者（RAGL），该图形将传播风险，地理依赖性和时间信息考虑在内，以更好地探索时空依赖性，并使地区意识到相关地区的流行状况。 RAGL还可以与外部资源（例如人类流动性）相结合，以进一步提高预测性能。对五个现实世界流行有关的数据集（包括流感和Covid-19）进行的全面实验证明了我们提出的方法的有效性，并表明Epignn在RMSE中优于最先进的基线。

节点分类和图形分类是两个图形学习问题，分别预测节点的类标签和图形的类标签。图的节点通常代表现实世界实体，例如，社交网络中的用户或文档引用网络中的文档。在这项工作中，我们考虑了一个更具挑战性但实际上有用的设置，其中节点本身是图形实例。这导致了层次图的观点，该视角在许多领域（例如社交网络，生物网络和文档收集）中产生。我们在层次图中研究节点分类问题，其中“节点”是图形实例。由于标签通常受到限制，我们设计了一种新型的半监督溶液，名为Seal-CI。 Seal-CI采用了一个迭代框架，该框架需要轮流更新两个模块，一个模块在图形实例级别，另一个在层次图级别上进行。为了在不同级别的层次图之间执行一致性，我们提出了分层图共同信息（HGMI），并进一步提出了一种使用理论保证计算HGMI的方法。我们证明了该层次图建模的有效性以及在文本和社交网络数据上提出的密封CI方法。

单纯性神经网络（SNN）最近被出现为图表学习中最新方向，这扩大了从节点空间到图形上的单纯复合体的卷积体系结构的想法。在目前的实践中，单纯复合资源允许我们描述高阶交互和多节点图结构的节点中的节点之间的成对关系进行预先定位通过在卷积操作和新块Hodge-Laplacian之间建立连接时，我们提出了第一个用于链接预测的SNN。我们的新块单纯性复杂神经网络（BSCNET）模型通过系统地掺入不同尺寸的多个高阶图结构之间的突出相互作用来推广现有的图形卷积网络（GCN）框架。我们讨论BSCNET背后的理论基础，并说明了其在八个现实世界和合成数据集上的链接预测的实用性。我们的实验表明，BSCNETS在保持低计算成本的同时优于最先进的模型，同时保持最高的余量。最后，我们展示了BSCnets作为追踪Covid-19等传染病传播的新有前途的替代品，并测量医疗保障风险缓解策略的有效性。

保持个人特征和复杂的关系，广泛利用和研究了图表数据。通过更新和聚合节点的表示，能够捕获结构信息，图形神经网络（GNN）模型正在获得普及。在财务背景下，该图是基于实际数据构建的，这导致复杂的图形结构，因此需要复杂的方法。在这项工作中，我们在最近的财务环境中对GNN模型进行了全面的审查。我们首先将普通使用的财务图分类并总结每个节点的功能处理步骤。然后，我们总结了每个地图类型的GNN方法，每个区域的应用，并提出一些潜在的研究领域。

Data-efficient learning on graphs (GEL) is essential in real-world applications. Existing GEL methods focus on learning useful representations for nodes, edges, or entire graphs with ``small'' labeled data. But the problem of data-efficient learning for subgraph prediction has not been explored. The challenges of this problem lie in the following aspects: 1) It is crucial for subgraphs to learn positional features to acquire structural information in the base graph in which they exist. Although the existing subgraph neural network method is capable of learning disentangled position encodings, the overall computational complexity is very high. 2) Prevailing graph augmentation methods for GEL, including rule-based, sample-based, adaptive, and automated methods, are not suitable for augmenting subgraphs because a subgraph contains fewer nodes but richer information such as position, neighbor, and structure. Subgraph augmentation is more susceptible to undesirable perturbations. 3) Only a small number of nodes in the base graph are contained in subgraphs, which leads to a potential ``bias'' problem that the subgraph representation learning is dominated by these ``hot'' nodes. By contrast, the remaining nodes fail to be fully learned, which reduces the generalization ability of subgraph representation learning. In this paper, we aim to address the challenges above and propose a Position-Aware Data-Efficient Learning framework for subgraph neural networks called PADEL. Specifically, we propose a novel node position encoding method that is anchor-free, and design a new generative subgraph augmentation method based on a diffused variational subgraph autoencoder, and we propose exploratory and exploitable views for subgraph contrastive learning. Extensive experiment results on three real-world datasets show the superiority of our proposed method over state-of-the-art baselines.

顺序推荐是推荐系统的广泛流行的主题。现有的作品有助于提高基于各种方法的顺序推荐系统的预测能力，例如经常性网络和自我关注机制。然而，他们未能发现和区分项目之间的各种关系，这可能是激励用户行为的潜在因素。在本文中，我们提出了一个边缘增强的全面解散图神经网络（EGD-GNN）模型，以捕获全局项目表示和本地用户意图学习项目之间的关系信息。在全球级别，我们通过所有序列构建全局链接图来模拟项目关系。然后，频道感知的解缠绕学习层被设计成将边缘信息分解为不同的信道，这可以聚合以将目标项从其邻居表示。在本地层面，我们应用一个变化的自动编码器框架来学习用户在当前序列上的意图。我们在三个现实世界数据集中评估我们提出的方法。实验结果表明，我们的模型可以通过最先进的基线获得至关重要的改进，能够区分项目特征。

Graph Neural Networks (GNNs) have attracted increasing attention in recent years and have achieved excellent performance in semi-supervised node classification tasks. The success of most GNNs relies on one fundamental assumption, i.e., the original graph structure data is available. However, recent studies have shown that GNNs are vulnerable to the complex underlying structure of the graph, making it necessary to learn comprehensive and robust graph structures for downstream tasks, rather than relying only on the raw graph structure. In light of this, we seek to learn optimal graph structures for downstream tasks and propose a novel framework for semi-supervised classification. Specifically, based on the structural context information of graph and node representations, we encode the complex interactions in semantics and generate semantic graphs to preserve the global structure. Moreover, we develop a novel multi-measure attention layer to optimize the similarity rather than prescribing it a priori, so that the similarity can be adaptively evaluated by integrating measures. These graphs are fused and optimized together with GNN towards semi-supervised classification objective. Extensive experiments and ablation studies on six real-world datasets clearly demonstrate the effectiveness of our proposed model and the contribution of each component.

Influence Maximization (IM) is a classical combinatorial optimization problem, which can be widely used in mobile networks, social computing, and recommendation systems. It aims at selecting a small number of users such that maximizing the influence spread across the online social network. Because of its potential commercial and academic value, there are a lot of researchers focusing on studying the IM problem from different perspectives. The main challenge comes from the NP-hardness of the IM problem and \#P-hardness of estimating the influence spread, thus traditional algorithms for overcoming them can be categorized into two classes: heuristic algorithms and approximation algorithms. However, there is no theoretical guarantee for heuristic algorithms, and the theoretical design is close to the limit. Therefore, it is almost impossible to further optimize and improve their performance. With the rapid development of artificial intelligence, the technology based on Machine Learning (ML) has achieved remarkable achievements in many fields. In view of this, in recent years, a number of new methods have emerged to solve combinatorial optimization problems by using ML-based techniques. These methods have the advantages of fast solving speed and strong generalization ability to unknown graphs, which provide a brand-new direction for solving combinatorial optimization problems. Therefore, we abandon the traditional algorithms based on iterative search and review the recent development of ML-based methods, especially Deep Reinforcement Learning, to solve the IM problem and other variants in social networks. We focus on summarizing the relevant background knowledge, basic principles, common methods, and applied research. Finally, the challenges that need to be solved urgently in future IM research are pointed out.

本文研究了用于无监督场景的图形神经网络（GNN）的节点表示。具体地，我们推导了理论分析，并在不适当定义的监督信号时，在不同的图形数据集中提供关于GNN的非稳定性能的实证演示。 GNN的性能取决于节点特征平滑度和图形结构的局部性。为了平滑通过图形拓扑和节点功能测量的节点接近度的差异，我们提出了帆 - 一个小说\下划线{s} elf- \下划线{a} u段图对比度\下划线{i} ve \ nignline {l}收入框架，使用两个互补的自蒸馏正则化模块，\ emph {Ie}，内部和图间知识蒸馏。我们展示了帆在各种图形应用中的竞争性能。即使使用单个GNN层，Sail也在各种基准数据集中持续竞争或更好的性能，与最先进的基线相比。

最近，图形神经网络（GNN）通过利用图形结构和节点特征的知识来表现出图表表示的显着性能。但是，他们中的大多数都有两个主要限制。首先，GNN可以通过堆叠更多的层来学习高阶结构信息，但由于过度光滑的问题，无法处理较大的深度。其次，由于昂贵的计算成本和高内存使用情况，在大图上应用这些方法并不容易。在本文中，我们提出了节点自适应特征平滑（NAFS），这是一种简单的非参数方法，该方法构建了没有参数学习的节点表示。 NAFS首先通过特征平滑提取每个节点及其不同啤酒花的邻居的特征，然后自适应地结合了平滑的特征。此外，通过不同的平滑策略提取的平滑特征的合奏可以进一步增强构建的节点表示形式。我们在两个不同的应用程序方案上对四个基准数据集进行实验：节点群集和链接预测。值得注意的是，具有功能合奏的NAFS优于这些任务上最先进的GNN，并减轻上述大多数基于学习的GNN对应物的两个限制。