manifesting a repeating n-gram. Tu et al. [187] and Kong et al. [87] analyze this phenomenon under
the name “over-translation”, that is, a repetitive appearance of words that were not in the source
text. Conversely, under-translation is skipping the words that need to be translated [187]. Finally,
abrupt jumps to the end of the sequence and outputs that remain mostly in the source language are
also examples of hallucinatory content [95].
SurveyofHallucinationinNatural Language Generation