Towards the automatic learning of idiomatic prepositional phrases

The objective of this work is to automatically determine, in an unsupervised manner, Spanish prepositional phrases of the type preposition - nominal phrase - preposition (P-NP-P) that behave in a sentence as a lexical unit and their semantic and syntactic properties cannot be deduced from the corresponding properties of each simple form, e.g., par medio de (by means of), a fin de (in order to), con respecto a (with respect to). We show that idiomatic P-NP-P combinations have some statistical properties distinct from those of usual idiomatic collocations. We also explore a way to differentiate P-NP-P combinations that could perform either as a regular prepositional phrase or as idiomatic prepositional phrase.