As you can see we have 1 unmatched entity: "U.S." is a hallucinated entity in the summary, that does not exist in the article.
Deep learning based generation is [prone to hallucinate](https://arxiv.org/pdf/2202.03629.pdf) unintended text. These hallucinations degrade
system performance and fail to meet user expectations in many real-world scenarios. By applying entity matching, we can improve this problem
for the downstream task of summary generation.