  Logical reasoning is a fundamental aspect of human intelligence and a key
component of tasks like problem-solving and decision-making. Recent
advancements have enabled Large Language Models (LLMs) to potentially exhibit
reasoning capabilities, but complex logical reasoning remains a challenge. The
state-of-the-art, solver-augmented language models, use LLMs to parse natural
language logical questions into symbolic representations first and then adopt
external logical solvers to take in the symbolic representations and output the
answers. Despite their impressive performance, any parsing errors will
inevitably result in the failure of the execution of the external logical
solver and no answer to the logical questions. In this paper, we introduce
LoGiPT, a novel language model that directly emulates the reasoning processes
of logical solvers and bypasses the parsing errors by learning to strict
adherence to solver syntax and grammar. LoGiPT is fine-tuned on a newly
constructed instruction-tuning dataset derived from revealing and refining the
invisible reasoning process of deductive solvers. Experimental results on two
public deductive reasoning datasets demonstrate that LoGiPT outperforms
state-of-the-art solver-augmented LMs and few-shot prompting methods on
competitive LLMs like ChatGPT or GPT-4.
