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Main Authors: Gao, Zhiqi, Ge, Albert, Berenbeim, Alexander, Bastian, Nathaniel D., Sala, Frederic
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.21751
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author Gao, Zhiqi
Ge, Albert
Berenbeim, Alexander
Bastian, Nathaniel D.
Sala, Frederic
author_facet Gao, Zhiqi
Ge, Albert
Berenbeim, Alexander
Bastian, Nathaniel D.
Sala, Frederic
contents Text-to-optimization requires two separable capabilities: modeling -- choosing the right optimization structure -- and binding -- grounding every coefficient, index, and parameter in the concrete problem data. We study this via Text2Opt-Bench, a scalable benchmark of solver-verified optimization problems spanning 12 categories, from textbook linear programs to stochastic and multi-objective formulations with up to thousands of variables. Across 10+ models, we find that accuracy collapses as instance data grows, even when the formulation itself is simple. We call this the effective binding limit. We address this via a simple inference-time approach, BIND, which externalizes numeric data to structured files so the model binds data programmatically rather than transcribing from the prompt. BIND improves GPT-5-Nano from 59.1% to 82.4% accuracy, matching pass@5 (82.0%) at lower token cost than pass@1, and GPT-5 from 86.2% to 95.8%. Furthermore, we validate our hypothesis by finetuning a model exclusively on binding and show that it outperforms end-to-end SFT and RL across three structurally distinct optimization categories, with a 1.5B binding specialist alone matching a 7B end-to-end baseline.
format Preprint
id arxiv_https___arxiv_org_abs_2605_21751
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Models Can Model, But Can't Bind: Structured Grounding in Text-to-Optimization
Gao, Zhiqi
Ge, Albert
Berenbeim, Alexander
Bastian, Nathaniel D.
Sala, Frederic
Machine Learning
Text-to-optimization requires two separable capabilities: modeling -- choosing the right optimization structure -- and binding -- grounding every coefficient, index, and parameter in the concrete problem data. We study this via Text2Opt-Bench, a scalable benchmark of solver-verified optimization problems spanning 12 categories, from textbook linear programs to stochastic and multi-objective formulations with up to thousands of variables. Across 10+ models, we find that accuracy collapses as instance data grows, even when the formulation itself is simple. We call this the effective binding limit. We address this via a simple inference-time approach, BIND, which externalizes numeric data to structured files so the model binds data programmatically rather than transcribing from the prompt. BIND improves GPT-5-Nano from 59.1% to 82.4% accuracy, matching pass@5 (82.0%) at lower token cost than pass@1, and GPT-5 from 86.2% to 95.8%. Furthermore, we validate our hypothesis by finetuning a model exclusively on binding and show that it outperforms end-to-end SFT and RL across three structurally distinct optimization categories, with a 1.5B binding specialist alone matching a 7B end-to-end baseline.
title Models Can Model, But Can't Bind: Structured Grounding in Text-to-Optimization
topic Machine Learning
url https://arxiv.org/abs/2605.21751