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Autori principali: Klypa, Roman, Cherednichenko, Oleksandr
Natura: Preprint
Pubblicazione: 2026
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Accesso online:https://arxiv.org/abs/2605.00195
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author Klypa, Roman
Cherednichenko, Oleksandr
author_facet Klypa, Roman
Cherednichenko, Oleksandr
contents Supervised Fine-Tuning (SFT) is essential for aligning Large Language Models (LLMs) with user intent, yet it is believed to suppress generative diversity. Although this reduction is frequently referenced, formal empirical testing of the phenomenon remains limited. The expressiveness of LLMs by itself was addressed by multiple prior methods. Their varying perspectives suggest that deeper investigation could yield further improvements. In this study, we attribute the decline to two primary drivers: the neglect of low-frequency patterns within fine-tuning datasets and the forgetting of preexisting knowledge. Motivated by our theoretical analysis, we develop Tempered Focal (TOFU) loss, a novel objective that addresses both stated challenges simultaneously. Our extensive evaluation confirms at scale that generation breadth narrows after SFT and strengthens the hypothesis explaining this effect. Across multiple models and benchmarks, we demonstrate that TOFU enhances output diversity while preserving high response quality, offering a principled approach to SFT.
format Preprint
id arxiv_https___arxiv_org_abs_2605_00195
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Diversity in Large Language Models under Supervised Fine-Tuning
Klypa, Roman
Cherednichenko, Oleksandr
Machine Learning
Supervised Fine-Tuning (SFT) is essential for aligning Large Language Models (LLMs) with user intent, yet it is believed to suppress generative diversity. Although this reduction is frequently referenced, formal empirical testing of the phenomenon remains limited. The expressiveness of LLMs by itself was addressed by multiple prior methods. Their varying perspectives suggest that deeper investigation could yield further improvements. In this study, we attribute the decline to two primary drivers: the neglect of low-frequency patterns within fine-tuning datasets and the forgetting of preexisting knowledge. Motivated by our theoretical analysis, we develop Tempered Focal (TOFU) loss, a novel objective that addresses both stated challenges simultaneously. Our extensive evaluation confirms at scale that generation breadth narrows after SFT and strengthens the hypothesis explaining this effect. Across multiple models and benchmarks, we demonstrate that TOFU enhances output diversity while preserving high response quality, offering a principled approach to SFT.
title Diversity in Large Language Models under Supervised Fine-Tuning
topic Machine Learning
url https://arxiv.org/abs/2605.00195