MEMETRON: Metaheuristic Mechanisms for Test-time Response Optimization of Large Language Models

Fuente: arXiv
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Main Authors: Nguyen, Son The, Tulabandhula, Theja
Format: Preprint
Published: 2025
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author Nguyen, Son The
Tulabandhula, Theja
author_facet Nguyen, Son The
Tulabandhula, Theja
contents Large language models (LLMs) are increasingly used for both open-ended and structured tasks, yet their inference-time behavior is still largely dictated by heuristic decoding strategies such as greedy search, sampling, or reranking. These methods provide limited control and do not explicitly optimize for task-specific objectives. We introduce MEMETRON, a task-agnostic framework that formulates LLM decoding as a discrete black-box optimization problem. MEMETRON leverages hybrid metaheuristic algorithms, GENETRON and ANNETRON, to search the response space, guided by reward models and contextual operations performed by the LLM itself. This approach enables efficient discovery of high-reward responses without requiring model retraining or gradient access. The framework is modular and generalizes across diverse tasks, requiring only a reward function and lightweight prompt templates. We evaluate our framework on the critical human preference alignment task and demonstrate that it significantly outperforms standard decoding and reranking methods, highlighting its potential to improve alignment without model retraining.
format Preprint
id arxiv_https___arxiv_org_abs_2506_08643
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MEMETRON: Metaheuristic Mechanisms for Test-time Response Optimization of Large Language Models
Nguyen, Son The
Tulabandhula, Theja
Computation and Language
Large language models (LLMs) are increasingly used for both open-ended and structured tasks, yet their inference-time behavior is still largely dictated by heuristic decoding strategies such as greedy search, sampling, or reranking. These methods provide limited control and do not explicitly optimize for task-specific objectives. We introduce MEMETRON, a task-agnostic framework that formulates LLM decoding as a discrete black-box optimization problem. MEMETRON leverages hybrid metaheuristic algorithms, GENETRON and ANNETRON, to search the response space, guided by reward models and contextual operations performed by the LLM itself. This approach enables efficient discovery of high-reward responses without requiring model retraining or gradient access. The framework is modular and generalizes across diverse tasks, requiring only a reward function and lightweight prompt templates. We evaluate our framework on the critical human preference alignment task and demonstrate that it significantly outperforms standard decoding and reranking methods, highlighting its potential to improve alignment without model retraining.
title MEMETRON: Metaheuristic Mechanisms for Test-time Response Optimization of Large Language Models
topic Computation and Language
url https://arxiv.org/abs/2506.08643