Hallucination is Inevitable: An Innate Limitation of Large Language Models

Fuente: arXiv
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Autori principali: Xu, Ziwei, Jain, Sanjay, Kankanhalli, Mohan
Natura: Preprint
Pubblicazione: 2024
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author Xu, Ziwei
Jain, Sanjay
Kankanhalli, Mohan
author_facet Xu, Ziwei
Jain, Sanjay
Kankanhalli, Mohan
contents Hallucination has been widely recognized to be a significant drawback for large language models (LLMs). There have been many works that attempt to reduce the extent of hallucination. These efforts have mostly been empirical so far, which cannot answer the fundamental question whether it can be completely eliminated. In this paper, we formalize the problem and show that it is impossible to eliminate hallucination in LLMs. Specifically, we define a formal world where hallucination is defined as inconsistencies between a computable LLM and a computable ground truth function. By employing results from learning theory, we show that LLMs cannot learn all the computable functions and will therefore inevitably hallucinate if used as general problem solvers. Since the formal world is a part of the real world which is much more complicated, hallucinations are also inevitable for real world LLMs. Furthermore, for real world LLMs constrained by provable time complexity, we describe the hallucination-prone tasks and empirically validate our claims. Finally, using the formal world framework, we discuss the possible mechanisms and efficacies of existing hallucination mitigators as well as the practical implications on the safe deployment of LLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2401_11817
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hallucination is Inevitable: An Innate Limitation of Large Language Models
Xu, Ziwei
Jain, Sanjay
Kankanhalli, Mohan
Computation and Language
Artificial Intelligence
Machine Learning
Hallucination has been widely recognized to be a significant drawback for large language models (LLMs). There have been many works that attempt to reduce the extent of hallucination. These efforts have mostly been empirical so far, which cannot answer the fundamental question whether it can be completely eliminated. In this paper, we formalize the problem and show that it is impossible to eliminate hallucination in LLMs. Specifically, we define a formal world where hallucination is defined as inconsistencies between a computable LLM and a computable ground truth function. By employing results from learning theory, we show that LLMs cannot learn all the computable functions and will therefore inevitably hallucinate if used as general problem solvers. Since the formal world is a part of the real world which is much more complicated, hallucinations are also inevitable for real world LLMs. Furthermore, for real world LLMs constrained by provable time complexity, we describe the hallucination-prone tasks and empirically validate our claims. Finally, using the formal world framework, we discuss the possible mechanisms and efficacies of existing hallucination mitigators as well as the practical implications on the safe deployment of LLMs.
title Hallucination is Inevitable: An Innate Limitation of Large Language Models
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2401.11817