UCCA poses a challenge for existing parsing techniques, as it exhibits reentrancy (resulting in DAG structures), discontinuous structures and non-terminal nodes corresponding to complex semantic units.
using better input encoding allowing virtual look-ahead and look-behind in the token representation, TUPA BiLSTM obtains substantially higher scores than TUPA MLP and all other parsers, on both primary and remote edges, both in the in-domain and out-of-domain settings.