SpecFuse: Ensembling Large Language Models via Next-Segment Prediction

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Main Authors: Lv, Bo, Liu, Nayu, Tang, Chen, Liu, Xin, Yu, Yue, Luo, Ping
Format: Preprint
Published: 2024
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author Lv, Bo
Liu, Nayu
Tang, Chen
Liu, Xin
Yu, Yue
Luo, Ping
author_facet Lv, Bo
Liu, Nayu
Tang, Chen
Liu, Xin
Yu, Yue
Luo, Ping
contents Ensembles of generative large language models (LLMs) are a promising way to compensate for individual model limitations, integrating the strengths of different LLMs. Existing LLM ensemble methods, however, face limitations such as first-token delay and challenges in long-range semantic collaboration between models, Moreover, they typically assume equal voting weights for all models during ensemble, ignoring task-specific performance differences among models. In this work, we propose SpecEM, a training-free, plug-and-play LLM ensemble framework that dynamically adjusts each model's model contribution in real time based on task performance. Inspired by speculative decoding, SpecEM iteratively performs drafting and verification, allowing models to collaborate semantically at the segment level for integrated output. Furthermore, we introduce an online feedback mechanism with multiplicative weight updates, where each model's voting weight is adjusted on-the-fly according to how often it outperforms others during verification stage, ensuring that stronger models exert greater influence during ensembling. Experimental results on five LLM families (ranging from 7B to 72B parameters) and six benchmark datasets, spanning open-domain instruction following, reasoning, commonsense, demonstrate consistent performance improvements compared to state-of-the-art LLM ensemble methods. Our code is available at https://github.com/lvbotenbest/SpecEM.
format Preprint
id arxiv_https___arxiv_org_abs_2412_07380
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle SpecFuse: Ensembling Large Language Models via Next-Segment Prediction
Lv, Bo
Liu, Nayu
Tang, Chen
Liu, Xin
Yu, Yue
Luo, Ping
Computation and Language
Artificial Intelligence
Ensembles of generative large language models (LLMs) are a promising way to compensate for individual model limitations, integrating the strengths of different LLMs. Existing LLM ensemble methods, however, face limitations such as first-token delay and challenges in long-range semantic collaboration between models, Moreover, they typically assume equal voting weights for all models during ensemble, ignoring task-specific performance differences among models. In this work, we propose SpecEM, a training-free, plug-and-play LLM ensemble framework that dynamically adjusts each model's model contribution in real time based on task performance. Inspired by speculative decoding, SpecEM iteratively performs drafting and verification, allowing models to collaborate semantically at the segment level for integrated output. Furthermore, we introduce an online feedback mechanism with multiplicative weight updates, where each model's voting weight is adjusted on-the-fly according to how often it outperforms others during verification stage, ensuring that stronger models exert greater influence during ensembling. Experimental results on five LLM families (ranging from 7B to 72B parameters) and six benchmark datasets, spanning open-domain instruction following, reasoning, commonsense, demonstrate consistent performance improvements compared to state-of-the-art LLM ensemble methods. Our code is available at https://github.com/lvbotenbest/SpecEM.
title SpecFuse: Ensembling Large Language Models via Next-Segment Prediction
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2412.07380