G-Sim: Generative Simulations with Large Language Models and Gradient-Free Calibration

Fuente: arXiv
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Hauptverfasser: Holt, Samuel, Luyten, Max Ruiz, Berthon, Antonin, van der Schaar, Mihaela
Format: Preprint
Veröffentlicht: 2025
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author Holt, Samuel
Luyten, Max Ruiz
Berthon, Antonin
van der Schaar, Mihaela
author_facet Holt, Samuel
Luyten, Max Ruiz
Berthon, Antonin
van der Schaar, Mihaela
contents Constructing robust simulators is essential for asking "what if?" questions and guiding policy in critical domains like healthcare and logistics. However, existing methods often struggle, either failing to generalize beyond historical data or, when using Large Language Models (LLMs), suffering from inaccuracies and poor empirical alignment. We introduce G-Sim, a hybrid framework that automates simulator construction by synergizing LLM-driven structural design with rigorous empirical calibration. G-Sim employs an LLM in an iterative loop to propose and refine a simulator's core components and causal relationships, guided by domain knowledge. This structure is then grounded in reality by estimating its parameters using flexible calibration techniques. Specifically, G-Sim can leverage methods that are both likelihood-free and gradient-free with respect to the simulator, such as gradient-free optimization for direct parameter estimation or simulation-based inference for obtaining a posterior distribution over parameters. This allows it to handle non-differentiable and stochastic simulators. By integrating domain priors with empirical evidence, G-Sim produces reliable, causally-informed simulators, mitigating data-inefficiency and enabling robust system-level interventions for complex decision-making.
format Preprint
id arxiv_https___arxiv_org_abs_2506_09272
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle G-Sim: Generative Simulations with Large Language Models and Gradient-Free Calibration
Holt, Samuel
Luyten, Max Ruiz
Berthon, Antonin
van der Schaar, Mihaela
Machine Learning
68T05, 68U20, 62F15
I.2.6; I.6.5; G.3
Constructing robust simulators is essential for asking "what if?" questions and guiding policy in critical domains like healthcare and logistics. However, existing methods often struggle, either failing to generalize beyond historical data or, when using Large Language Models (LLMs), suffering from inaccuracies and poor empirical alignment. We introduce G-Sim, a hybrid framework that automates simulator construction by synergizing LLM-driven structural design with rigorous empirical calibration. G-Sim employs an LLM in an iterative loop to propose and refine a simulator's core components and causal relationships, guided by domain knowledge. This structure is then grounded in reality by estimating its parameters using flexible calibration techniques. Specifically, G-Sim can leverage methods that are both likelihood-free and gradient-free with respect to the simulator, such as gradient-free optimization for direct parameter estimation or simulation-based inference for obtaining a posterior distribution over parameters. This allows it to handle non-differentiable and stochastic simulators. By integrating domain priors with empirical evidence, G-Sim produces reliable, causally-informed simulators, mitigating data-inefficiency and enabling robust system-level interventions for complex decision-making.
title G-Sim: Generative Simulations with Large Language Models and Gradient-Free Calibration
topic Machine Learning
68T05, 68U20, 62F15
I.2.6; I.6.5; G.3
url https://arxiv.org/abs/2506.09272