Tokenised Flow Matching for Hierarchical Simulation Based Inference

Fuente: arXiv
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Hauptverfasser: Charles, Giovanni, Santoni, Cosmo, Flaxman, Seth, Semenova, Elizaveta
Format: Preprint
Veröffentlicht: 2026
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author Charles, Giovanni
Santoni, Cosmo
Flaxman, Seth
Semenova, Elizaveta
author_facet Charles, Giovanni
Santoni, Cosmo
Flaxman, Seth
Semenova, Elizaveta
contents The cost of simulator evaluations is a key practical bottleneck for Simulation Based Inference (SBI). In hierarchical settings with shared global parameters and exchangeable site-level parameters and observations, this structure can be exploited to improve simulation efficiency. Existing hierarchical SBI approaches factorise the posterior yet still simulate across multiple sites per training sample; We instead explore likelihood factorisation (LF) to train from single-site simulations. In LF sampling we learn a per-site neural surrogate of the simulator and then assemble synthetic multi-site observations to amortise inference for the full hierarchical posterior. Building on this, we propose Tokenised Flow Matching for Posterior Estimation (TFMPE), a tokenised flow matching approach that supports function-valued observations through likelihood factorisation. To enable systematic evaluation, we introduce a benchmark for hierarchical SBI. We validate TFMPE on this benchmark and on realistic infectious disease and computational fluid dynamics models, finding well-calibrated posteriors while reducing computational cost.
format Preprint
id arxiv_https___arxiv_org_abs_2604_20723
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Tokenised Flow Matching for Hierarchical Simulation Based Inference
Charles, Giovanni
Santoni, Cosmo
Flaxman, Seth
Semenova, Elizaveta
Machine Learning
Artificial Intelligence
The cost of simulator evaluations is a key practical bottleneck for Simulation Based Inference (SBI). In hierarchical settings with shared global parameters and exchangeable site-level parameters and observations, this structure can be exploited to improve simulation efficiency. Existing hierarchical SBI approaches factorise the posterior yet still simulate across multiple sites per training sample; We instead explore likelihood factorisation (LF) to train from single-site simulations. In LF sampling we learn a per-site neural surrogate of the simulator and then assemble synthetic multi-site observations to amortise inference for the full hierarchical posterior. Building on this, we propose Tokenised Flow Matching for Posterior Estimation (TFMPE), a tokenised flow matching approach that supports function-valued observations through likelihood factorisation. To enable systematic evaluation, we introduce a benchmark for hierarchical SBI. We validate TFMPE on this benchmark and on realistic infectious disease and computational fluid dynamics models, finding well-calibrated posteriors while reducing computational cost.
title Tokenised Flow Matching for Hierarchical Simulation Based Inference
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2604.20723