Scalable, Explainable and Provably Robust Anomaly Detection with One-Step Flow Matching

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Hauptverfasser: Li, Zhong, Huang, Qi, Zhu, Yuxuan, Yang, Lincen, Amiri, Mohammad Mohammadi, van Stein, Niki, van Leeuwen, Matthijs
Format: Preprint
Veröffentlicht: 2025
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author Li, Zhong
Huang, Qi
Zhu, Yuxuan
Yang, Lincen
Amiri, Mohammad Mohammadi
van Stein, Niki
van Leeuwen, Matthijs
author_facet Li, Zhong
Huang, Qi
Zhu, Yuxuan
Yang, Lincen
Amiri, Mohammad Mohammadi
van Stein, Niki
van Leeuwen, Matthijs
contents We introduce Time-Conditioned Contraction Matching (TCCM), a novel method for semi-supervised anomaly detection in tabular data. TCCM is inspired by flow matching, a recent generative modeling framework that learns velocity fields between probability distributions and has shown strong performance compared to diffusion models and generative adversarial networks. Instead of directly applying flow matching as originally formulated, TCCM builds on its core idea -- learning velocity fields between distributions -- but simplifies the framework by predicting a time-conditioned contraction vector toward a fixed target (the origin) at each sampled time step. This design offers three key advantages: (1) a lightweight and scalable training objective that removes the need for solving ordinary differential equations during training and inference; (2) an efficient scoring strategy called one time-step deviation, which quantifies deviation from expected contraction behavior in a single forward pass, addressing the inference bottleneck of existing continuous-time models such as DTE (a diffusion-based model with leading anomaly detection accuracy but heavy inference cost); and (3) explainability and provable robustness, as the learned velocity field operates directly in input space, making the anomaly score inherently feature-wise attributable; moreover, the score function is Lipschitz-continuous with respect to the input, providing theoretical guarantees under small perturbations. Extensive experiments on the ADBench benchmark show that TCCM strikes a favorable balance between detection accuracy and inference cost, outperforming state-of-the-art methods -- especially on high-dimensional and large-scale datasets. The source code is available at our GitHub repository.
format Preprint
id arxiv_https___arxiv_org_abs_2510_18328
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Scalable, Explainable and Provably Robust Anomaly Detection with One-Step Flow Matching
Li, Zhong
Huang, Qi
Zhu, Yuxuan
Yang, Lincen
Amiri, Mohammad Mohammadi
van Stein, Niki
van Leeuwen, Matthijs
Machine Learning
Artificial Intelligence
We introduce Time-Conditioned Contraction Matching (TCCM), a novel method for semi-supervised anomaly detection in tabular data. TCCM is inspired by flow matching, a recent generative modeling framework that learns velocity fields between probability distributions and has shown strong performance compared to diffusion models and generative adversarial networks. Instead of directly applying flow matching as originally formulated, TCCM builds on its core idea -- learning velocity fields between distributions -- but simplifies the framework by predicting a time-conditioned contraction vector toward a fixed target (the origin) at each sampled time step. This design offers three key advantages: (1) a lightweight and scalable training objective that removes the need for solving ordinary differential equations during training and inference; (2) an efficient scoring strategy called one time-step deviation, which quantifies deviation from expected contraction behavior in a single forward pass, addressing the inference bottleneck of existing continuous-time models such as DTE (a diffusion-based model with leading anomaly detection accuracy but heavy inference cost); and (3) explainability and provable robustness, as the learned velocity field operates directly in input space, making the anomaly score inherently feature-wise attributable; moreover, the score function is Lipschitz-continuous with respect to the input, providing theoretical guarantees under small perturbations. Extensive experiments on the ADBench benchmark show that TCCM strikes a favorable balance between detection accuracy and inference cost, outperforming state-of-the-art methods -- especially on high-dimensional and large-scale datasets. The source code is available at our GitHub repository.
title Scalable, Explainable and Provably Robust Anomaly Detection with One-Step Flow Matching
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2510.18328