AIGMob:Conditional Generative AI for Fine-grained Urban Mobility Simulation
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1.SIMformer: Single-Layer Vanilla Transformer Can Learn Free-Space Trajectory Similarity
- 关键词:
- NETWORKS
- Yang, Chuang;Jiang, Renhe;Xu, Xiaohang;Xiao, Chuan;Sezaki, Kaoru
- 《PROCEEDINGS OF THE VLDB ENDOWMENT》
- 2024年
- 18卷
- 2期
- 期刊
Free-space trajectory similarity calculation, e.g., DTW, Hausdorff, and Fr & eacute;chet, often incur quadratic time complexity, thus learning- based methods have been proposed to accelerate the computation. The core idea is to train an encoder to transform trajectories into representation vectors and then compute vector similarity to approximate the ground truth. However, existing methods face dual challenges of effectiveness and efficiency: 1) they all utilize Euclidean distance to compute representation similarity, which leads to the severe curse of dimensionality issue - reducing the distinguishability among representations and significantly affecting the accuracy of subsequent similarity search tasks; 2) most of them are trained in triplets manner and often necessitate additional information which downgrades the efficiency; 3) previous studies, while emphasizing the scalability in terms of efficiency, overlooked the deterioration of effectiveness when the dataset size grows. To cope with these issues, we propose a simple, yet accurate, fast, scalable model that only uses a single-layer vanilla transformer encoder as the feature extractor and employs tailored representation similarity functions to approximate various ground truth similarity measures. Extensive experiments demonstrate our model significantly mitigates the curse of dimensionality issue and outperforms the state-of-the-arts in effectiveness, efficiency, and scalability.
...2.Spatial-Temporal-Decoupled Masked Pre-training for Spatiotemporal Forecasting
- 关键词:
- ;
- Gao, Haotian;Jiang, Renhe;Dong, Zheng;Deng, Jinliang;Ma, Yuxin;Song, Xuan
- 《33rd International Joint Conference on Artificial Intelligence, IJCAI 2024》
- 2024年
- August 3, 2024 - August 9, 2024
- Jeju, Korea, Republic of
- 会议
Spatiotemporal forecasting techniques are significant for various domains such as transportation, energy, and weather. Accurate prediction of spatiotemporal series remains challenging due to the complex spatiotemporal heterogeneity. In particular, current end-to-end models are limited by input length and thus often fall into spatiotemporal mirage, i.e., similar input time series followed by dissimilar future values and vice versa. To address these problems, we propose a novel self-supervised pre-training framework Spatial-Temporal-Decoupled Masked Pre-training (STD-MAE) that employs two decoupled masked autoencoders to reconstruct spatiotemporal series along the spatial and temporal dimensions. Rich-context representations learned through such reconstruction could be seamlessly integrated by downstream predictors with arbitrary architectures to augment their performances. A series of quantitative and qualitative evaluations on four widely used benchmarks (PEMS03, PEMS04, PEMS07, and PEMS08) are conducted to validate the state-of-the-art performance of STD-MAE. Codes are available at https://github.com/Jimmy-7664/STD-MAE. © 2024 International Joint Conferences on Artificial Intelligence. All rights reserved.
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