Deep Dependency Graph Conversion in English

This paper presents a method for the automatic conversion of constituency trees into deep dependency graphs consisting of primary, secondary, and semantic relations. Our work is distinguished from previous work concerning the generation of shallow dependency trees such that it generates dependency graphs incorporating deep structures in which relations stay consistent regardless of their surface positions, and derives relations between out-of-domain arguments, caused by syntactic variations such as open clause, relative clause, or coordination, and their predicates so the complete argument structures are represented for both verbal and non-verbal predicates. Our deep dependency graph conversion recovers important argument relations that would be missed by dependency tree conversion, and merges syntactic and semantic relations into one unified representation, which can reduce the bundle of developing another layer of annotation dedicated for predicate argument structures. Our graph conversion method is applied to six corpora in English and generated over 4.6M dependency graphs covering 20 different genres.1