Without a notion of head, two dependency trees will represent one RST tree consisting of one multinuclear relation.
assuming some convention to determine the head in an RST tree will result in a dependency structure that represents two RST c-trees; for instance, assuming that a tree consisting of one multinuclear relation has its head in the leftmost argument will mean that the RST trees [a N , b] and [a N , b N ] yield the same unlabeled dependency structure, a → b. Consequently, RST non-terminal constituents have been translated as dependencies with some information loss; see for example .