Graph neural networks (GNNs) are the primary tool for processing graph-structured data. Unfortunately, the most commonly used GNNs, called Message Passing Neural Networks (MPNNs) suffer from several fundamental limitations. To overcome these limitations, recent works have adapted the idea of positional encodings to graph data. This paper draws inspiration from the recent success of Laplacian-based positional encoding and defines a novel family of positional encoding schemes for graphs. We accomplish this by generalizing the optimization problem that defines the Laplace embedding to more general dissimilarity functions rather than the 2-norm used in the original formulation. This family of positional encodings is then instantiated by considering p-norms. We discuss a method for calculating these positional encoding schemes, implement it in PyTorch and demonstrate how the resulting positional encoding captures different properties of the graph. Furthermore, we demonstrate that this novel family of positional encodings can improve the expressive power of MPNNs. Lastly, we present preliminary experimental results.
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图形神经网络(GNN)在许多基于图的学​​习任务中表现出很大的优势,但通常无法准确预测基于任务的节点集,例如链接/主题预测等。最近,许多作品通过使用随机节点功能或节点距离特征来解决此问题。但是,它们的收敛速度缓慢,预测不准确或高复杂性。在这项工作中,我们重新访问允许使用位置编码(PE)技术(例如Laplacian eigenmap,deepwalk等)的节点的位置特征。 。在这里,我们以原则性的方式研究了这些问题,并提出了一种可证明的解决方案,这是一类用严格数学分析的钉子的GNN层。 PEG使用单独的频道来更新原始节点功能和位置功能。 PEG施加置换量比W.R.T.原始节点功能并施加$ O(P)$(正交组)均值W.R.T.位置特征同时特征,其中$ p $是二手位置特征的维度。在8个现实世界网络上进行的广泛链接预测实验证明了PEG在概括和可伸缩性方面的优势。
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In the last few years, graph neural networks (GNNs) have become the standard toolkit for analyzing and learning from data on graphs. This emerging field has witnessed an extensive growth of promising techniques that have been applied with success to computer science, mathematics, biology, physics and chemistry. But for any successful field to become mainstream and reliable, benchmarks must be developed to quantify progress. This led us in March 2020 to release a benchmark framework that i) comprises of a diverse collection of mathematical and real-world graphs, ii) enables fair model comparison with the same parameter budget to identify key architectures, iii) has an open-source, easy-to-use and reproducible code infrastructure, and iv) is flexible for researchers to experiment with new theoretical ideas. As of December 2022, the GitHub repository has reached 2,000 stars and 380 forks, which demonstrates the utility of the proposed open-source framework through the wide usage by the GNN community. In this paper, we present an updated version of our benchmark with a concise presentation of the aforementioned framework characteristics, an additional medium-sized molecular dataset AQSOL, similar to the popular ZINC, but with a real-world measured chemical target, and discuss how this framework can be leveraged to explore new GNN designs and insights. As a proof of value of our benchmark, we study the case of graph positional encoding (PE) in GNNs, which was introduced with this benchmark and has since spurred interest of exploring more powerful PE for Transformers and GNNs in a robust experimental setting.
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A current goal in the graph neural network literature is to enable transformers to operate on graph-structured data, given their success on language and vision tasks. Since the transformer's original sinusoidal positional encodings (PEs) are not applicable to graphs, recent work has focused on developing graph PEs, rooted in spectral graph theory or various spatial features of a graph. In this work, we introduce a new graph PE, Graph Automaton PE (GAPE), based on weighted graph-walking automata (a novel extension of graph-walking automata). We compare the performance of GAPE with other PE schemes on both machine translation and graph-structured tasks, and we show that it generalizes several other PEs. An additional contribution of this study is a theoretical and controlled experimental comparison of many recent PEs in graph transformers, independent of the use of edge features.
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最新提出的基于变压器的图形模型的作品证明了香草变压器用于图形表示学习的不足。要了解这种不足,需要研究变压器的光谱分析是否会揭示其对其表现力的见解。类似的研究已经确定,图神经网络(GNN)的光谱分析为其表现力提供了额外的观点。在这项工作中,我们系统地研究并建立了变压器领域中的空间和光谱域之间的联系。我们进一步提供了理论分析,并证明了变压器中的空间注意机制无法有效捕获所需的频率响应,因此,固有地限制了其在光谱空间中的表现力。因此,我们提出了feta,该框架旨在在整个图形频谱(即图形的实际频率成分)上进行注意力类似于空间空间中的注意力。经验结果表明,FETA在标准基准的所有任务中为香草变压器提供均匀的性能增益,并且可以轻松地扩展到具有低通特性的基于GNN的模型(例如GAT)。
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Graph Neural Networks (GNNs) have shown great potential in the field of graph representation learning. Standard GNNs define a local message-passing mechanism which propagates information over the whole graph domain by stacking multiple layers. This paradigm suffers from two major limitations, over-squashing and poor long-range dependencies, that can be solved using global attention but significantly increases the computational cost to quadratic complexity. In this work, we propose an alternative approach to overcome these structural limitations by leveraging the ViT/MLP-Mixer architectures introduced in computer vision. We introduce a new class of GNNs, called Graph MLP-Mixer, that holds three key properties. First, they capture long-range dependency and mitigate the issue of over-squashing as demonstrated on the Long Range Graph Benchmark (LRGB) and the TreeNeighbourMatch datasets. Second, they offer better speed and memory efficiency with a complexity linear to the number of nodes and edges, surpassing the related Graph Transformer and expressive GNN models. Third, they show high expressivity in terms of graph isomorphism as they can distinguish at least 3-WL non-isomorphic graphs. We test our architecture on 4 simulated datasets and 7 real-world benchmarks, and show highly competitive results on all of them.
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我们提出了一个食谱,讲述了如何建立具有线性复杂性和最先进的结果的一般,功能可扩展的(GPS)图形变压器,并在各种基准测试基准上。 Graph Transformers(GTS)在图形表示学习领域中获得了多种近期出版物的知名度,但它们对构成良好的位置或结构编码的共同基础以及与众不同的区别。在本文中,我们总结了具有更清晰的定义的不同类型的编码,并将其分类为$ \ textit {local} $,$ \ textit {global} $或$ \ textit {fextit {ferseal} $。此外,GTS仍被限制在具有数百个节点的小图上,我们提出了第一个具有复杂性线性的体系结构对节点和边缘$ O(n+e)$的数量,通过将局部实质汇总从完全 - 连接的变压器。我们认为,这种解耦并不会对表现性产生负面影响,而我们的体系结构是图形的通用函数近似器。我们的GPS配方包括选择3种主要成分:(i)位置/结构编码,(ii)局部消息通讯机制和(iii)全局注意机制。我们构建和开源一个模块化框架$ \ textit {graphgps} $,该{GraphGps} $支持多种类型的编码,并且在小图和大图中提供效率和可扩展性。我们在11个基准测试上测试了我们的体系结构,并对所有这些基准显示出非常具竞争力的结果,展示了由模块化和不同策略组合获得的经验益处。
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在过去的几年中,已经开发了图形绘图技术,目的是生成美学上令人愉悦的节点链接布局。最近,利用可区分损失功能的使用已为大量使用梯度下降和相关优化算法铺平了道路。在本文中,我们提出了一个用于开发图神经抽屉(GND)的新框架,即依靠神经计算来构建有效且复杂的图的机器。 GND是图形神经网络(GNN),其学习过程可以由任何提供的损失函数(例如图形图中通常使用的损失函数)驱动。此外,我们证明,该机制可以由通过前馈神经网络计算的损失函数来指导,并根据表达美容特性的监督提示,例如交叉边缘的最小化。在这种情况下,我们表明GNN可以通过位置功能很好地丰富与未标记的顶点处理。我们通过为边缘交叉构建损失函数来提供概念验证,并在提议的框架下工作的不同GNN模型之间提供定量和定性的比较。
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Optimization of directed acyclic graph (DAG) structures has many applications, such as neural architecture search (NAS) and probabilistic graphical model learning. Encoding DAGs into real vectors is a dominant component in most neural-network-based DAG optimization frameworks. Currently, most DAG encoders use an asynchronous message passing scheme which sequentially processes nodes according to the dependency between nodes in a DAG. That is, a node must not be processed until all its predecessors are processed. As a result, they are inherently not parallelizable. In this work, we propose a Parallelizable Attention-based Computation structure Encoder (PACE) that processes nodes simultaneously and encodes DAGs in parallel. We demonstrate the superiority of PACE through encoder-dependent optimization subroutines that search the optimal DAG structure based on the learned DAG embeddings. Experiments show that PACE not only improves the effectiveness over previous sequential DAG encoders with a significantly boosted training and inference speed, but also generates smooth latent (DAG encoding) spaces that are beneficial to downstream optimization subroutines. Our source code is available at \url{https://github.com/zehao-dong/PACE}
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变压器架构最近在图表表示学习中引起了人们的注意,因为它自然地克服了图神经网络(GNN)的几个局限性,避免了它们严格的结构电感偏置,而仅通过位置编码来编码图形结构。在这里,我们表明,具有位置编码的变压器生成的节点表示不一定捕获它们之间的结构相似性。为了解决这个问题,我们提出了结构感知的变压器,这是一类简单而灵活的图形变压器,建立在新的自我发项机制的基础上。这一新的自我注意力通过在计算注意力之前提取植根于每个节点的子图表来结合结构信息。我们提出了几种自动生成子图表表示的方法,并从理论上说明结果表示至少与子图表一样表现力。从经验上讲,我们的方法在五个图预测基准上实现了最先进的性能。我们的结构感知框架可以利用任何现有的GNN提取子图表表示,我们表明它系统地改善了相对于基本GNN模型的性能,成功地结合了GNN和变形金刚的优势。我们的代码可在https://github.com/borgwardtlab/sat上找到。
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变压器架构已成为许多域中的主导选择,例如自然语言处理和计算机视觉。然而,与主流GNN变体相比,它对图形水平预测的流行排行榜没有竞争表现。因此,它仍然是一个谜,变形金机如何对图形表示学习表现良好。在本文中,我们通过提出了基于标准变压器架构构建的Gragemer来解决这一神秘性,并且可以在广泛的图形表示学习任务中获得优异的结果,特别是在最近的OGB大规模挑战上。我们在图中利用变压器的关键洞察是有效地将图形的结构信息有效地编码到模型中。为此,我们提出了几种简单但有效的结构编码方法,以帮助Gramemormer更好的模型图形结构数据。此外,我们在数学上表征了Gramemormer的表现力,并展示了我们编码图形结构信息的方式,许多流行的GNN变体都可以被涵盖为GrameRormer的特殊情况。
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图形神经网络(GNN)已被证明可以实现竞争结果,以解决与图形相关的任务,例如节点和图形分类,链接预测和节点以及各种域中的图形群集。大多数GNN使用消息传递框架,因此称为MPNN。尽管有很有希望的结果,但据报道,MPNN会遭受过度平滑,过度阵型和不足的影响。文献中已经提出了图形重新布线和图形池作为解决这些局限性的解决方案。但是,大多数最先进的图形重新布线方法无法保留该图的全局拓扑,因此没有可区分(电感),并且需要调整超参数。在本文中,我们提出了Diffwire,这是一个在MPNN中进行图形重新布线的新型框架,它通过利用LOV \'ASZ绑定来原理,完全可区分且无参数。我们的方法通过提出两个新的,mpnns中的新的互补层来提供统一的图形重新布线:首先,ctlayer,一个学习通勤时间并将其用作边缘重新加权的相关函数;其次,Gaplayer是优化光谱差距的图层,具体取决于网络的性质和手头的任务。我们从经验上验证了我们提出的方法的价值,并使用基准数据集分别验证了这些层的每个层以进行图形分类。 Diffwire将通勤时间的可学习性汇集到相关的曲率定义,为发展更具表现力的MPNN的发展打开了大门。
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图形神经网络(GNN)已成为一种学习关系数据的强大技术。由于他们执行的消息传递步骤数量相对有限 - 因此一个较小的接收领域,人们对通过结合基础图的结构方面来提高其表现力引起了极大的兴趣。在本文中,我们探讨了亲和力措施作为图形神经网络中的特征,特别是由随机步行引起的措施,包括有效的阻力,击球和通勤时间。我们根据这些功能提出消息传递网络,并评估其在各种节点和图形属性预测任务上的性能。我们的体系结构具有较低的计算复杂性,而我们的功能对于基础图的排列不变。我们计算的措施使网络可以利用图表的连接性能,从而使我们能够超过相关的基准,用于各种任务,通常具有更少的消息传递步骤。在OGB-LSC-PCQM4MV1的最大公共图形回归数据集之一中,我们在编写时获得了最著名的单模验证MAE。
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The Transformer architecture has become a dominant choice in many domains, such as natural language processing and computer vision. Yet, it has not achieved competitive performance on popular leaderboards of graph-level prediction compared to mainstream GNN variants. Therefore, it remains a mystery how Transformers could perform well for graph representation learning. In this paper, we solve this mystery by presenting Graphormer, which is built upon the standard Transformer architecture, and could attain excellent results on a broad range of graph representation learning tasks, especially on the recent OGB Large-Scale Challenge. Our key insight to utilizing Transformer in the graph is the necessity of effectively encoding the structural information of a graph into the model. To this end, we propose several simple yet effective structural encoding methods to help Graphormer better model graph-structured data. Besides, we mathematically characterize the expressive power of Graphormer and exhibit that with our ways of encoding the structural information of graphs, many popular GNN variants could be covered as the special cases of Graphormer. The code and models of Graphormer will be made publicly available at https://github.com/Microsoft/Graphormer.
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由于其数值益处增加及其坚实的数学背景,光谱聚类方法的非线性重构近来的关注。我们在$ p $ -norm中提出了一种新的直接多道谱聚类算法,以$ p \ in(1,2] $。计算图表的多个特征向量的问题$ p $ -laplacian,标准的非线性概括Graph Laplacian,被重用作为Grassmann歧管的无约束最小化问题。$ P $的价值以伪连续的方式减少,促进对应于最佳图形的稀疏解决方案载体作为$ P $接近。监测单调减少平衡图削减了我们从$ P $ -Levels获得的最佳可用解决方案的保证。我们展示了我们算法在各种人工测试案件中的算法的有效性和准确性。我们的数值和比较结果具有各种状态-Art聚类方法表明,所提出的方法在均衡的图形剪切度量和标签分配的准确性方面取得高质量的集群。此外,我们进行S面部图像和手写字符分类的束缚,以展示现实数据集中的适用性。
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基于变压器的模型已在各个领域(例如自然语言处理和计算机视觉)中广泛使用并实现了最先进的性能。最近的作品表明,变压器也可以推广到图形结构化数据。然而,由于技术挑战,诸如节点数量和非本地聚集的技术挑战之类的技术挑战,因此成功限于小规模图,这通常会导致对常规图神经网络的概括性能。在本文中,为了解决这些问题,我们提出了可变形的图形变压器(DGT),以动态采样的键和值对进行稀疏注意。具体而言,我们的框架首先构建具有各种标准的多个节点序列,以考虑结构和语义接近。然后,将稀疏的注意力应用于节点序列,以减少计算成本,以学习节点表示。我们还设计简单有效的位置编码,以捕获节点之间的结构相似性和距离。实验表明,我们的新型图形变压器始终胜过现有的基于变压器的模型,并且与8个图形基准数据集(包括大型图形)的最新模型相比,与最新的模型相比表现出竞争性能。
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基于1-HOP邻居之间的消息传递(MP)范式交换信息的图形神经网络(GNN),以在每一层构建节点表示。原则上,此类网络无法捕获在图形上学习给定任务的可能或必需的远程交互(LRI)。最近,人们对基于变压器的图的开发产生了越来越多的兴趣,这些方法可以考虑超出原始稀疏结构以外的完整节点连接,从而实现了LRI的建模。但是,仅依靠1跳消息传递的MP-gnn与位置特征表示形式结合使用时通常在几个现有的图形基准中表现得更好,因此,限制了Transferter类似体系结构的感知效用和排名。在这里,我们介绍了5个图形学习数据集的远程图基准(LRGB):Pascalvoc-SP,Coco-SP,PCQM-Contact,Peptides-Func和肽结构,可以说需要LRI推理以在给定的任务中实现强大的性能。我们基准测试基线GNN和Graph Transformer网络,以验证捕获长期依赖性的模型在这些任务上的性能明显更好。因此,这些数据集适用于旨在捕获LRI的MP-GNN和Graph Transformer架构的基准测试和探索。
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图形神经网络(GNNS)对图表上的半监督节点分类展示了卓越的性能,结果是它们能够同时利用节点特征和拓扑信息的能力。然而,大多数GNN隐含地假设曲线图中的节点和其邻居的标签是相同或一致的,其不包含在异质图中,其中链接节点的标签可能不同。因此,当拓扑是非信息性的标签预测时,普通的GNN可以显着更差,而不是在每个节点上施加多层Perceptrons(MLPS)。为了解决上述问题,我们提出了一种新的$ -laplacian基于GNN模型,称为$ ^ P $ GNN,其消息传递机制来自离散正则化框架,并且可以理论上解释为多项式图的近似值在$ p $ -laplacians的频谱域上定义过滤器。光谱分析表明,新的消息传递机制同时用作低通和高通滤波器,从而使$ ^ P $ GNNS对同性恋和异化图有效。关于现实世界和合成数据集的实证研究验证了我们的调查结果,并证明了$ ^ P $ GNN明显优于异交基准的几个最先进的GNN架构,同时在同性恋基准上实现竞争性能。此外,$ ^ p $ gnns可以自适应地学习聚合权重,并且对嘈杂的边缘具有强大。
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Learning node embeddings that capture a node's position within the broader graph structure is crucial for many prediction tasks on graphs. However, existing Graph Neural Network (GNN) architectures have limited power in capturing the position/location of a given node with respect to all other nodes of the graph. Here we propose Position-aware Graph Neural Networks (P-GNNs), a new class of GNNs for computing position-aware node embeddings. P-GNN first samples sets of anchor nodes, computes the distance of a given target node to each anchor-set, and then learns a non-linear distance-weighted aggregation scheme over the anchor-sets. This way P-GNNs can capture positions/locations of nodes with respect to the anchor nodes. P-GNNs have several advantages: they are inductive, scalable, and can incorporate node feature information. We apply P-GNNs to multiple prediction tasks including link prediction and community detection. We show that P-GNNs consistently outperform state of the art GNNs, with up to 66% improvement in terms of the ROC AUC score.Node embedding methods can be categorized into Graph Neural Networks (GNNs) approaches (Scarselli et al., 2009),
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近年来,基于Weisfeiler-Leman算法的算法和神经架构,是一个众所周知的Graph同构问题的启发式问题,它成为具有图形和关系数据的机器学习的强大工具。在这里,我们全面概述了机器学习设置中的算法的使用,专注于监督的制度。我们讨论了理论背景,展示了如何将其用于监督的图形和节点表示学习,讨论最近的扩展,并概述算法的连接(置换 - )方面的神经结构。此外,我们概述了当前的应用和未来方向,以刺激进一步的研究。
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