Effectively long-distance dependencies in French : annotation and parsing evaluation

We describe the annotation of cases of extraction in French, whose previous annotations in the available French treebanks were insufficient to recover the correct predicate-argument dependency between the extracted element and its head. These cases are special cases of LDDs, that we call effectively longdistance dependencies (eLDDs), in which the extracted element is indeed separated from its head by one or more intervening heads (instead of zero, one or more for the general case). We found that extraction of a dependent of a finite verb is very rarely an eLDD (one case out of 420 000 tokens), but eLDDs corresponding to extraction out of infinitival phrase is more frequent (one third of all occurrences of accusative relative pronoun que), and eLDDs with extraction out of NPs are quite common (2/3 of the occurrences of relative pronoun dont). We also use the annotated data in statistical dependency parsing experiments, and compare several parsing architectures able to recover non-local governors for extracted elements.