Before revision:  However, besides well-known issues from which such metrics suffer (Callison-Burch et al., 2006; Novikova et al., 2017), we show that an additional problem arises when applied for AMR-to-text evaluation because mapping from the more abstract domain of AMR to the more concrete domain of sentences allows for manifold sentence realizations.
After revision:  However, besides well-known issues from which such metrics suffer , an additional problem arises when applied for AMR-to-text evaluation because mapping from the more abstract domain of AMR to the more concrete domain of sentences allows for manifold sentence realizations.