an example. When generating “Sun”, the posterior is high for document 2 which mentions “The
Sun Also Rises”. Similarly, document 1 dominates the posterior when “A Farewell to Arms” is
generated. Intriguingly, after the ﬁrst token of each book is generated, the document posterior ﬂattens.
This observation suggests that the generator can complete the titles without depending on speciﬁc
documents. In other words, the model’s parametric knowledge is sufﬁcient to complete the titles. We
ﬁnd evidence for this hypothesis by feeding the BART-only baseline with the partial decoding "The
Sun. BART completes the generation "The Sun Also Rises" is a novel by this author of "The Sun
Also Rises" indicating the title "The Sun Also Rises" is stored in BART’s parameters. Similarly,
BART will complete the partial decoding "The Sun Also Rises" is a novel by this author of "A
with "The Sun Also Rises" is a novel by this author of "A Farewell to Arms". This example shows
Retrieval-AugmentedGenerationfor Knowledge-IntensiveNLPTasks