Constrained Decoding for Structural Error Suppression in Dependency Tree Generation with Large Language Models
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Abstract
In the field of syntactic parsing, fine-tuning large language models to generate a sentence's syntactic structure in bracket form is a promising approach. Existing fine-tuned models demonstrate high values of syntax parsing metrics; however, in some cases they generate an incorrect bracket sequence (for example, with an unbalanced number of opening and closing parentheses). Therefore, this study aims to develop a method to reduce the number of incorrectly generated sequences. A system of constraints has been introduced on the set of tokens generated at each stage of the large language model. The implemented method was tested on four fine-tuned models (adapted and non-adapted with 4 and 8 billion parameters) on the SynTagRus dependency tree dataset. For all models, the number of incorrectly generated sequences decreased. However, some sentences were not parsed, because the LLMs generated an excessively long token sequence and were interrupted. The code for this study is publicly available.
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References
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