Perhaps the most interesting reason to study the canonical graph-based and transition-based models is that even though they appear to be quite different theoretically (see Section 2), recent empirical studies show that both obtain similar parsing accuracies on a variety of languages.
the dependency graph given at termination is guaranteed to be acyclic and projective and to satisfy dependency graph conditions 1-3, which means that it can always be turned into a well-formed dependency graph by adding arcs (0, i, l r ) for every node i = 0 that is a root in the output graph (where l r is a special label for root modifiers).