The main research problem associated with the evidence selection sub-task is how to retrieve
evidence from the world knowledge. Most of the literature leverages Wikipedia as the knowledge
source [97, 182, 221], which is only a small part of world knowledge. Other literature attempts to use
the whole web as the knowledge source [44, 123]. However, this method leads to another research
problem – “how to ensure the trustworthiness of the information we use from the web” [58]. Source-
level methods that leverages the meta-information of the web source (e.g., web traffic, PageRank or
URL structure) have been proposed to deal with this trustworthiness issue [7, 144, 145]. Addressing
the aforementioned issues to allow evidence selection against world knowledge will be an important
future research direction.
SurveyofHallucinationinNatural Language Generation