ACM Comput. Surv., Vol. 1, No. 1, Article . Publication date: February 2022.

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Ziwei Ji, et al.

Organization of this Survey. The remainder of this survey is organized as follows. Section 2
∼ Section 6 provide an overview of the hallucination problem in NLG by discussing the definition
and categorization, contributors, metrics, and mitigation methods of hallucinations, respectively.
The second part of our survey discusses the hallucination problem associated with specific NLG
tasks: abstractive summarization in Section 7, dialogue generation in Section 8, GQA in Section 9,
data-to-text generation in Section 10, machine translation in Section 11, and VL generation in
Section 12. Finally, we conclude the whole survey in Section 13.
SurveyofHallucinationinNatural Language Generation