Graph transformers have emerged as a promising architecture for a variety of graph learning and representation tasks. Despite their successes, though, it remains challenging to scale graph transformers to large graphs while maintaining accuracy competitive with message-passing networks. In this paper, we introduce Exphormer, a framework for building powerful and scalable graph transformers. Exphormer consists of a sparse attention mechanism based on two mechanisms: virtual global nodes and expander graphs, whose mathematical characteristics, such as spectral expansion, pseduorandomness, and sparsity, yield graph transformers with complexity only linear in the size of the graph, while allowing us to prove desirable theoretical properties of the resulting transformer models. We show that incorporating Exphormer into the recently-proposed GraphGPS framework produces models with competitive empirical results on a wide variety of graph datasets, including state-of-the-art results on three datasets. We also show that Exphormer can scale to datasets on larger graphs than shown in previous graph transformer architectures. Code can be found at \url{https://github.com/hamed1375/Exphormer}.
University of California, Santa Barbara（加州大学圣巴巴拉分校）
Transformers are the mainstream of NLP applications and are becoming increasingly popular in other domains such as Computer Vision. Despite the improvements in model quality, the enormous computation costs make Transformers difficult at deployment, especially when the sequence length is large in emerging applications. Processing attention mechanism as the essential component of Transformer is the bottleneck of execution due to the quadratic complexity. Prior art explores sparse patterns in attention to support long sequence modeling, but those pieces of work are on static or fixed patterns. We…
University of Michigan, Ann Arbor（密歇根大学安娜堡分校）；Microsoft（微软）
Sparsely activated transformers, such as Mixture of Experts (MoE), have received great interest due to their outrageous scaling capability which enables dramatical increases in model size without significant increases in computational cost. To achieve this, MoE models replace the feedforward sub-layer with Mixture-of-Experts sub-layer in transformers and use a gating network to route each token to its assigned experts. Since the common practice for efficient training of such models requires distributing experts and tokens across different machines, this routing strategy often incurs huge cross…
Recently, Transformer networks have redefined the state of the art in many NLP tasks. However, these models suffer from quadratic computational cost in the input sequence length $n$ to compute pairwise attention in each layer. This has prompted recent research into sparse Transformers that sparsify the connections in the attention layers. While empirically promising for long sequences, fundamental questions remain unanswered: Can sparse Transformers approximate any arbitrary sequence-to-sequence function, similar to their dense counterparts? How does the sparsity pattern and the sparsity level…
Despite their remarkable achievement, gigantic transformers encounter significant drawbacks, including exorbitant computational and memory footprints during training, as well as severe collapse evidenced by a high degree of parameter redundancy. Sparsely-activated Mixture-of-Experts (SMoEs) have shown promise to mitigate the issue of training efficiency, yet they are prone to (1) redundant experts due to representational collapse; and (2) poor expert scalability for inference and downstream fine-tuning, primarily due to overfitting of the learned routing policy to the number of activated exper…
University of California Irvine（加州大学欧文分校）；Purdue University（普渡大学）；Brookhaven National Laboratory（布鲁克海文国家实验室）；The University of Utah（犹他大学）
We propose GLassoformer, a novel and efficient transformer architecture leveraging group Lasso regularization to reduce the number of queries of the standard self-attention mechanism. Due to the sparsified queries, GLassoformer is more computationally efficient than the standard transformers. On the power grid post-fault voltage prediction task, GLassoformer shows remarkably better prediction than many existing benchmark algorithms in terms of accuracy and stability.
SAF3R: Dynamic Sparse Attention for Feed-Forward 3D Reconstruction Transformers
University of Pittsburgh（匹兹堡大学）；University of Arizona（亚利桑那大学）；Tongji University（同济大学）；University of Central Florida（中佛罗里达大学）；University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）
Recent work on the lottery ticket hypothesis has produced highly sparse Transformers for NMT while maintaining BLEU. However, it is unclear how such pruning techniques affect a model's learned representations. By probing Transformers with more and more low-magnitude weights pruned away, we find that complex semantic information is first to be degraded. Analysis of internal activations reveals that higher layers diverge most over the course of pruning, gradually becoming less complex than their dense counterparts. Meanwhile, early layers of sparse models begin to perform more encoding. Attentio…
University of Michigan（密歇根大学）；NVIDIA Corporation（英伟达公司）
Transformer-based neural networks have achieved state-of-the-art task performance in a number of machine learning domains including natural language processing and computer vision. To further improve their accuracy, recent work has explored the integration of dynamic behavior into these networks in the form of mixture-of-expert (MoE) layers. In this paper, we explore the introduction of MoE layers to optimize a different metric: inference latency. We introduce a novel system named PLANER that takes an existing Transformer-based network and a user-defined latency target and produces an optimize…
Sparse Transformer Architectures via Regularized Wasserstein Proximal Operator with $L_1$ Prior
Department of Mathematics, University of California, Los Angeles, CA, USA（加州大学洛杉矶分校数学系）；Department of Mathematics, University of South Carolina, Columbia, SC, USA（南卡罗来纳大学数学系）
Dimensional Collapse in Transformer Attention Outputs: A Challenge for Sparse Dictionary Learning
Shanghai Innovation Institute, Shanghai, China（上海创新研究院）；OpenMOSS Team, School of Computer Science, Fudan University, Shanghai, China（开放MOSS团队，计算机科学学院，复旦大学）
Efficient Transformers have been developed for long sequence modeling, due to their subquadratic memory and time complexity. Sparse Transformer is a popular approach to improving the efficiency of Transformers by restricting self-attention to locations specified by the predefined sparse patterns. However, leveraging sparsity may sacrifice expressiveness compared to full-attention, when important token correlations are multiple hops away. To combine advantages of both the efficiency of sparse transformer and the expressiveness of full-attention Transformer, we propose \textit{Diffuser}, a new s…
Self-attention has recently been adopted for a wide range of sequence modeling problems. Despite its effectiveness, self-attention suffers from quadratic compute and memory requirements with respect to sequence length. Successful approaches to reduce this complexity focused on attending to local sliding windows or a small set of locations independent of content. Our work proposes to learn dynamic sparse attention patterns that avoid allocating computation and memory to attend to content unrelated to the query of interest. This work builds upon two lines of research: it combines the modeling fl…
Georgia Institute of Technology（佐治亚理工学院）；Microsoft（微软）
Sparsely activated models (SAMs), such as Mixture-of-Experts (MoE), can easily scale to have outrageously large amounts of parameters without significant increase in computational cost. However, SAMs are reported to be parameter inefficient such that larger models do not always lead to better performance. While most on-going research focuses on improving SAMs models by exploring methods of routing inputs to experts, our analysis reveals that such research might not lead to the solution we expect, i.e., the commonly-used routing methods based on gating mechanisms do not work better than randoml…
Stanford University（斯坦福大学）；Google Research（谷歌研究院）；University of Alberta（阿尔伯塔大学）
Transformers provide a class of expressive architectures that are extremely effective for sequence modeling. However, the key limitation of transformers is their quadratic memory and time complexity $\mathcal{O}(L^2)$ with respect to the sequence length in attention layers, which restricts application in extremely long sequences. Most existing approaches leverage sparsity or low-rank assumptions in the attention matrix to reduce cost, but sacrifice expressiveness. Instead, we propose Combiner, which provides full attention capability in each attention head while maintaining low computation and…
BERT4Traj: Transformer Based Trajectory Reconstruction for Sparse Mobility Data
University of Georgia（佐治亚大学）；Department of Geography University of Georgia（佐治亚大学地理系）；College of Public Health University of Georgia（佐治亚大学公共卫生学院）；University of Texas at Austin（德克萨斯大学奥斯汀分校）
University of British Columbia（不列颠哥伦比亚大学）；Carnegie Mellon University（卡内基梅隆大学）；Meta；CMU（卡内基梅隆大学）；Google Research（谷歌研究院）；UBC（不列颠哥伦比亚大学）；Amii（阿尔伯塔创新人工智能研究所）
The complex events observed at the NOvA long-baseline neutrino oscillation experiment contain vital information for understanding the most elusive particles in the standard model. The NOvA detectors observe interactions of neutrinos from the NuMI beam at Fermilab. Associating the particles produced in these interaction events to their source particles, a process known as reconstruction, is critical for accurately measuring key parameters of the standard model. Events may contain several particles, each producing sparse high-dimensional spatial observations, and current methods are limited to e…
Self-attention based Transformer has demonstrated the state-of-the-art performances in a number of natural language processing tasks. Self-attention is able to model long-term dependencies, but it may suffer from the extraction of irrelevant information in the context. To tackle the problem, we propose a novel model called \textbf{Explicit Sparse Transformer}. Explicit Sparse Transformer is able to improve the concentration of attention on the global context through an explicit selection of the most relevant segments. Extensive experimental results on a series of natural language processing an…
SSSLab, Dept. of CST China University of Petroleum-Beijing Beijing China（SSSLab，计算机科学与技术系中国石油大学（北京）北京中国）；Baidu Inc. Beijing China（百度公司北京中国）；School of Computer Science Shanghai Jiao Tong University Shanghai China（计算机科学学院上海交通大学上海中国）；China University of Petroleum-Beijing Beihang University Beijing China（中国石油大学（北京）北京航空航天大学北京中国）；China University of Petroleum-Beijing（中国石油大学（北京））；Beihang University（北京航空航天大学）；Baidu Inc.（百度公司）；Shanghai Jiao Tong University（上海交通大学）
University of Warsaw（华沙大学）；Google Research（谷歌研究院）；OpenAI
Large Transformer models yield impressive results on many tasks, but are expensive to train, or even fine-tune, and so slow at decoding that their use and study becomes out of reach. We address this problem by leveraging sparsity. We study sparse variants for all layers in the Transformer and propose Scaling Transformers, a family of next generation Transformer models that use sparse layers to scale efficiently and perform unbatched decoding much faster than the standard Transformer as we scale up the model size. Surprisingly, the sparse layers are enough to obtain the same perplexity as the s…
Learning on Transformers is Provable Low-Rank and Sparse: A One-layer Analysis
Rensselaer Polytechnic Institute（伦斯勒理工学院）；New Jersey Institute of Technology（新泽西理工学院）；Michigan State University（密歇根州立大学）；IBM Thomas J. Watson Research Center（IBM托马斯·J·沃森研究中心）
The Transformer has been an indispensable staple in deep learning. However, for real-life applications, it is very challenging to deploy efficient Transformers due to immense parameters and operations of models. To relieve this burden, exploiting sparsity is an effective approach to accelerate Transformers. Newly emerging Ampere GPUs leverage a 2:4 sparsity pattern to achieve model acceleration, while it can hardly meet the diverse algorithm and hardware constraints when deploying models. By contrast, we propose an algorithm-hardware co-optimized framework to flexibly and efficiently accelerat…
Transformers are powerful sequence models, but require time and memory that grows quadratically with the sequence length. In this paper we introduce sparse factorizations of the attention matrix which reduce this to $O(n \sqrt{n})$. We also introduce a) a variation on architecture and initialization to train deeper networks, b) the recomputation of attention matrices to save memory, and c) fast attention kernels for training. We call networks with these changes Sparse Transformers, and show they can model sequences tens of thousands of timesteps long using hundreds of layers. We use the same a…
TinyFormer: Efficient Transformer Design and Deployment on Tiny Devices
School of Computer Science and Engineering, Beihang University（北京航空航天大学计算机科学与工程学院）；Qingdao Research Institute, Beihang University（北京航空航天大学青岛研究所）；Department of Computer Science and Engineering, The Chinese University of Hong Kong（香港中文大学（深圳）计算机科学与工程系）；Fert Beijing Research Institute, School of Integrated Circuit Science and Engineering, Beihang University（北京航空航天大学集成电路科学与工程学院）
University of California, Santa Barbara（加州大学圣巴巴拉分校）；Saratoga High School（萨拉托加高中）；Toyota Technological Institute at Chicago（芝加哥丰田技术研究所）
Multimodal classification is a core task in human-centric machine learning. We observe that information is highly complementary across modalities, thus unimodal information can be drastically sparsified prior to multimodal fusion without loss of accuracy. To this end, we present Sparse Fusion Transformers (SFT), a novel multimodal fusion method for transformers that performs comparably to existing state-of-the-art methods while having greatly reduced memory footprint and computation cost. Key to our idea is a sparse-pooling block that reduces unimodal token sets prior to cross-modality modelin…
