AMRs can be seen as graphs connecting concepts by relations. Each concept is represented by a named instance. Co-reference is established by re-using these instances. For example, the AMRs corresponding to examples (1) and (2) above are given in Figure 1 . Note that, due to the bracketing, the variable b encapsulates the whole entity person :name "Bob" and not just person, i.e. b stands for a person with the name Bob. That there is a lot to gain in this area can be seen by applying the AMR evaluation suite of Damonte et al. (2017) , which calculates nine different metrics to evaluate AMR parsing, reentrancy being one of them. Out of the four systems that made these scores available (all scores reported in<cite> van Noord and Bos (2017)</cite> ), the reentrancy metric obtained the lowest F-score for three of them.