In <cite>our previous work</cite> (<cite>Zapirain et al., 2009</cite> ), we modelled SPs for pairs of predicates (verbs) and arguments, independently of the fact that the argument is a core argument (typically a noun) or an adjunct argument (typically a prepositional phrase). In contrast, (Litkowski and Hargraves, 2005) show that prepositions have SPs of their own, especially when functioning as adjuncts. We therefore decided to split SPs according to whether the potential argument is a Prepositional Phrase (PP) or a Noun Phrase (NP).