Features are defined in terms of arbitrary properties of the configuration c, including the state of the stack σ c , the input buffer β c , and the partially built dependency graph G c (represented in the configuration by the arc set A c ).
many features involve properties of the two target tokens, the token on top of the stack σ c (denoted σ 0 c ) and the first token in the input buffer β c (denoted β 0 c ), which are the two tokens that may become connected by a dependency arc through the transition out of c. The basic feature representation used for all languages in the CoNLL-X shared task included three groups of features: 5 r Part-of-speech features: Note in particular that features can be defined with respect to the partially built dependency graph G c .