Bridging Formal Language with Chain-of-Thought Reasoning to Geometry Problem Solving

Fuente: arXiv
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Main Authors: Yang, Tianyun, Li, Yunwen, Li, Ziniu, Lin, Zhihang, Sun, Ruoyu, Ding, Tian
Format: Preprint
Published: 2025
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author Yang, Tianyun
Li, Yunwen
Li, Ziniu
Lin, Zhihang
Sun, Ruoyu
Ding, Tian
author_facet Yang, Tianyun
Li, Yunwen
Li, Ziniu
Lin, Zhihang
Sun, Ruoyu
Ding, Tian
contents Large vision language models exhibit notable limitations on Geometry Problem Solving (GPS) because of their unreliable diagram interpretation and pure natural-language reasoning. A recent line of work mitigates this by using symbolic solvers: the model directly generates a formal program that a geometry solver can execute. However, this direct program generation lacks intermediate reasoning, making the decision process opaque and prone to errors. In this work, we explore a new approach that integrates Chain-of-Thought (CoT) with formal language. The model interleaves natural language reasoning with incremental emission of solver-executable code, producing a hybrid reasoning trace in which critical derivations are expressed in formal language. To teach this behavior at scale, we combine (1) supervised fine-tuning on an 11K newly developed synthetic dataset with interleaved natural language reasoning and automatic formalization, and (2) solver-in-the-loop reinforcement learning that jointly optimizes both the CoT narrative and the resulting program through outcome-based rewards. Built on Qwen2.5-VL-7B, our new model, named GF-Reasoner, achieves up to 15% accuracy improvements on standard GPS benchmarks, surpassing both 7B-scale peers and the much larger model Qwen2.5-VL-72B. By exploiting high-order geometric knowledge and offloading symbolic computation to the solver, the generated reasoning traces are noticeably shorter and cleaner. Furthermore, we present a comprehensive analysis of method design choices (e.g., reasoning paradigms, data synthesis, training epochs, etc.), providing actionable insights for future research.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09099
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Bridging Formal Language with Chain-of-Thought Reasoning to Geometry Problem Solving
Yang, Tianyun
Li, Yunwen
Li, Ziniu
Lin, Zhihang
Sun, Ruoyu
Ding, Tian
Machine Learning
Large vision language models exhibit notable limitations on Geometry Problem Solving (GPS) because of their unreliable diagram interpretation and pure natural-language reasoning. A recent line of work mitigates this by using symbolic solvers: the model directly generates a formal program that a geometry solver can execute. However, this direct program generation lacks intermediate reasoning, making the decision process opaque and prone to errors. In this work, we explore a new approach that integrates Chain-of-Thought (CoT) with formal language. The model interleaves natural language reasoning with incremental emission of solver-executable code, producing a hybrid reasoning trace in which critical derivations are expressed in formal language. To teach this behavior at scale, we combine (1) supervised fine-tuning on an 11K newly developed synthetic dataset with interleaved natural language reasoning and automatic formalization, and (2) solver-in-the-loop reinforcement learning that jointly optimizes both the CoT narrative and the resulting program through outcome-based rewards. Built on Qwen2.5-VL-7B, our new model, named GF-Reasoner, achieves up to 15% accuracy improvements on standard GPS benchmarks, surpassing both 7B-scale peers and the much larger model Qwen2.5-VL-72B. By exploiting high-order geometric knowledge and offloading symbolic computation to the solver, the generated reasoning traces are noticeably shorter and cleaner. Furthermore, we present a comprehensive analysis of method design choices (e.g., reasoning paradigms, data synthesis, training epochs, etc.), providing actionable insights for future research.
title Bridging Formal Language with Chain-of-Thought Reasoning to Geometry Problem Solving
topic Machine Learning
url https://arxiv.org/abs/2508.09099