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arXiv · 2406.00578

ContextFlow++: Generalist-Specialist Flow-based Generative Models with Mixed-Variable Context Encoding

Denis Gudovskiy·Tomoyuki Okuno·Yohei Nakata
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Abstract

Normalizing flow-based generative models have been widely used in applications where the exact density estimation is of major importance. Recent research proposes numerous methods to improve their expressivity. However, conditioning on a context is largely overlooked area in the bijective flow research. Conventional conditioning with the vector concatenation is limited to only a few flow types. More importantly, this approach cannot support a practical setup where a set of context-conditioned (specialist) models are trained with the fixed pretrained general-knowledge (generalist) model. We propose ContextFlow++ approach to overcome these limitations using an additive conditioning with explicit generalist-specialist knowledge decoupling. Furthermore, we support discrete contexts by the proposed mixed-variable architecture with context encoders. Particularly, our context encoder for discrete variables is a surjective flow from which the context-conditioned continuous variables are sampled. Our experiments on rotated MNIST-R, corrupted CIFAR-10C, real-world ATM predictive maintenance and SMAP unsupervised anomaly detection benchmarks show that the proposed ContextFlow++ offers faster stable training and achieves higher performance metrics. Our code is publicly available at https://github.com/gudovskiy/contextflow.

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Denis Gudovskiy, Tomoyuki Okuno, Yohei Nakata. 2024-06-02. ContextFlow++: Generalist-Specialist Flow-based Generative Models with Mixed-Variable Context Encoding. https://arxiv.org/abs/2406.00578

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