It's worth mentioning that dependency annotations for our problem exhibit a significant number of non-projective arcs (26%), meaning that entities involved in the part-of relation are non-adjacent (i.e., interleaved by other entities), as intuitively expected.
transition-based dependency parsing (tB) Given that our system needs to be able to handle non-projective dependency arcs, we employ a greedy transition-based parsing system (Nivre, 2009;Bohnet and Nivre, 2012) as the basis of our parser.