Elucidating the Design Choice of Probability Paths in Flow Matching for Forecasting
Soon Hoe Lim, Yijin Wang, Annan Yu, Emma Hart, Michael W. Mahoney, Xiaoye S. Li, N. Benjamin Erichson

TL;DR
This paper investigates how the choice of probability path models in flow matching affects probabilistic time series forecasting, proposing a new model that enhances performance and efficiency.
Contribution
The paper introduces a novel probability path model for flow matching that improves forecasting accuracy and training convergence, with practical efficiency during inference.
Findings
Faster convergence during training.
Improved predictive performance.
Efficient inference with few sampling steps.
Abstract
Flow matching has recently emerged as a powerful paradigm for generative modeling and has been extended to probabilistic time series forecasting in latent spaces. However, the impact of the specific choice of probability path model on forecasting performance remains under-explored. In this work, we demonstrate that forecasting spatio-temporal data with flow matching is highly sensitive to the selection of the probability path model. Motivated by this insight, we propose a novel probability path model designed to improve forecasting performance. Our empirical results across various dynamical system benchmarks show that our model achieves faster convergence during training and improved predictive performance compared to existing probability path models. Importantly, our approach is efficient during inference, requiring only a few sampling steps. This makes our proposed model practical for…
Peer Reviews
Decision·Submitted to ICLR 2025
1. The paper is well-written and accessible. 2. It presents a unified framework for probability path models in the context of flow matching and diffusion models, providing readers with a clearer overview of current generative model research.
1. The main contribution of the paper is a new probability path model for spatio-temporal data. However, the motivation behind this model is presented somewhat vaguely. A more formal and rigorous mathematical illustration would improve clarity. 2. There are numerous existing diffusion model-based methods for spatio-temporal data; a comparison with these methods would strengthen the paper. 3. The baselines all seem to use an encoder. An ablation study demonstrating the benefits of modeling in t
- The paper clearly and thoroughly discusses and compares the various kinds of probabilistic forecasting models, which are informative and insightful. - The proposed probability path model learns to connect consecutive time series samples, leading to faster convergence and more stable training. - The experiments are intensive, providing support for the proposed model.
- Some notations are a little bit confusing. For example, do $v_t$ in algorithm 1 and $v_s$ in algorithm 2 mean the same vector field? - The result for faster convergence and fewer sample steps comes empirically. It can benefit from more therotical derivations or insights for why the proposed probability path yileds better results.
THe ability to perform spatio-temporal forecasting is a major strenght. A novel theoretical framework for flow-based forecasting of spatio-temporal data. The probabilistic path is parametrized using a neural network, which results in the task to be solved in the form of second-order regression. By taking into account inherent correlations in spatio-temporal data, the proposed model improves upon the existing models of the kind. Extensive performance records, and comprehensive ablation study.
The main weakness is the choice of the framework. Stochastic processes and ODE based method are known to underperform for non-Gaussian distributions and non-stationary data. Especially, the gaussian probabiliy paths cannot deal with real-world data which exhibit fat-tailed distribution. The conditional probability paths and the marginalization of distributions are rather standard in GenAI. The performance metrics are all second-rder (MSE, Frobenius norm, peak signal to noise ratio, etc), which
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Taxonomy
TopicsTraffic Prediction and Management Techniques · Time Series Analysis and Forecasting
