Using PiTagger for Lemmatization and PoS Tagging of a Spontaneous Speech Corpus: C-Oral-Rom Italian

The automatic lemmatization and morpho-syntactic annotation of spoken language is a quite recent and complex task for Natural Language Processing. The state of the art on written corpora don't provide us with a satisfactory level of analysis regarding spontaneous spoken language (Uchimoto et al., 2002; Moreno & Guirao, 2003). The spontaneous speech corpus Italian C-ORALROM has been tagged with Part of Speech (Pos) and morpho-syntactic information, using and adapting an already existing tool trained on Italian written resources (PiTagger, developed by Eugenio Picchi, ILC-CNR Pisa). The incidence of spoken domain on the performance is within a 10% of errors detected in the manual evaluation procedure. Some issues concerning spoken language emerged. The definition of significant contexts for PoS statistics is to be provided by utterance boundaries; moreover, the relevance of a series of phenomena related to the prosodic parsing has been highlighted: fragmentation phenomena, a relative lack of information for all word adjacent to utterance boundaries; under-specification of PoS for words in connection to secondary prosodic breaks and one word utterances.