  This paper reduces discontinuous parsing to sequence labeling. It first shows
that existing reductions for constituent parsing as labeling do not support
discontinuities. Second, it fills this gap and proposes to encode tree
discontinuities as nearly ordered permutations of the input sequence. Third, it
studies whether such discontinuous representations are learnable. The
experiments show that despite the architectural simplicity, under the right
representation, the models are fast and accurate.

Computation and Language