TFTF: Training-Free Targeted Flow for Conditional Sampling

• URL: http://arxiv.org/abs/2602.12932v1
• Date: Fri, 13 Feb 2026 13:41:35 GMT
• Title: TFTF: Training-Free Targeted Flow for Conditional Sampling
• Authors: Qianqian Qu, Jun S. Liu,
• Abstract summary: We propose a training-free conditional sampling method for flow matching models based on importance sampling.<n>Because a nave application of importance sampling suffers from weighteneracy in high-dimensional settings, we modify and incorporate a resampling technique in sequential Monte Carlo.<n>Our framework requires no additional training, while providing theoretical guarantees of accuracy.
• Score: 1.4151684142137693
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We propose a training-free conditional sampling method for flow matching models based on importance sampling. Because a naïve application of importance sampling suffers from weight degeneracy in high-dimensional settings, we modify and incorporate a resampling technique in sequential Monte Carlo (SMC) during intermediate stages of the generation process. To encourage generated samples to diverge along distinct trajectories, we derive a stochastic flow with adjustable noise strength to replace the deterministic flow at the intermediate stage. Our framework requires no additional training, while providing theoretical guarantees of asymptotic accuracy. Experimentally, our method significantly outperforms existing approaches on conditional sampling tasks for MNIST and CIFAR-10. We further demonstrate the applicability of our approach in higher-dimensional, multimodal settings through text-to-image generation experiments on CelebA-HQ.

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