Precise Length Control in Large Language Models

Fuente: arXiv
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Main Authors: Butcher, Bradley, O'Keefe, Michael, Titchener, James
Format: Preprint
Published: 2024
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author Butcher, Bradley
O'Keefe, Michael
Titchener, James
author_facet Butcher, Bradley
O'Keefe, Michael
Titchener, James
contents Large Language Models (LLMs) are increasingly used in production systems, powering applications such as chatbots, summarization, and question answering. Despite their success, controlling the length of their response remains a significant challenge, particularly for tasks requiring structured outputs or specific levels of detail. In this work, we propose a method to adapt pre-trained decoder-only LLMs for precise control of response length. Our approach incorporates a secondary length-difference positional encoding (LDPE) into the input embeddings, which counts down to a user-set response termination length. Fine-tuning with LDPE allows the model to learn to terminate responses coherently at the desired length, achieving mean token errors of less than 3 tokens. We also introduce Max New Tokens++, an extension that enables flexible upper-bound length control, rather than an exact target. Experimental results on tasks such as question answering and document summarization demonstrate that our method enables precise length control without compromising response quality.
format Preprint
id arxiv_https___arxiv_org_abs_2412_11937
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Precise Length Control in Large Language Models
Butcher, Bradley
O'Keefe, Michael
Titchener, James
Computation and Language
I.2.7
Large Language Models (LLMs) are increasingly used in production systems, powering applications such as chatbots, summarization, and question answering. Despite their success, controlling the length of their response remains a significant challenge, particularly for tasks requiring structured outputs or specific levels of detail. In this work, we propose a method to adapt pre-trained decoder-only LLMs for precise control of response length. Our approach incorporates a secondary length-difference positional encoding (LDPE) into the input embeddings, which counts down to a user-set response termination length. Fine-tuning with LDPE allows the model to learn to terminate responses coherently at the desired length, achieving mean token errors of less than 3 tokens. We also introduce Max New Tokens++, an extension that enables flexible upper-bound length control, rather than an exact target. Experimental results on tasks such as question answering and document summarization demonstrate that our method enables precise length control without compromising response quality.
title Precise Length Control in Large Language Models
topic Computation and Language
I.2.7
url https://arxiv.org/abs/2412.11937