Event Factuality in Italian: Annotation of News Stories from the Ita-TimeBank
Authors: Anne-Lyse Minard, Alessandro Marchetti, Manuela Speranza (Fondazione Bruno Kessler, 2014)
Topic: Lexical and Semantic Resources and Analysis

Abstract
In this paper we present ongoing work devoted to the extension of the Ita-TimeBank (Caselli et al., 2011) with event factuality annotation on top of TimeML annotation, where event factuality is rep-resented on three main axes: time, polarity and certainty. We describe the annotation schema proposed for Italian and report on the results of our corpus analysis.

Introduction
In this work, we propose an annotation schema for factuality in Italian adapted from the schema for English developed in the NewsReader project1 (Tonelli et al., 2014) and describe the annotation performed on top of event annotation in the Ita-TimeBank (Caselli et al., 2011). We aim at the creation of a reference corpus for training and test-ing a factuality recognizer for Italian. The knowledge of the factual or non-factual na-ture of an event mentioned in a text is crucial for many applications (such as question answer-ing, information extraction and temporal reason-ing) because it allows us to recognize if an event refers to a real or to hypothetical situation, and en-ables us to assign it to its time of occurrence. In particular we are interested in the representation of information about a specific entity on a timeline, which enables easier access to related knowledge. The automatic creation of timelines requires the detection of situations and events in which target entities participate. To be able to place an event on a timeline, a system has to be able to select the events which happen or that are true at a certain point in time or in a time span. In a real context (such as the context of a newspaper article), the situations and events mentioned in texts can refer to real situations in the world, have no real coun-terpart, or have an uncertain nature. The FactBank guidelines are the reference guidelines for factuality in English and FactBank is the reference corpus (Sauri and Pustejovsky, 2009). More recently other guidelines and resources have been developed (Wonsever et al., 2012; van Son et al., 2014), but, to the best of our knowledge, no resources exist for event factuality in Italian.

Conclusion
In this paper we have presented an annotation schema of event factuality in Italian and the an-notation task done on the Ita-TimeBank. In our schema, factuality information is represented by three attributes: time of the event, polarity of the statement and certainty of the source about the event. We have selected from the Ita-TimeBank 170 documents containing 10,205 events and we have annotated them following the pro-posed annotation schema. The annotated corpus is freely available for non commer-cial purposes from https://hlt.fbk.eu/ technologies/fact-ita-bank. The resource has been used to develop a system based on machine learning for the automatic iden-tification of factuality in Italian. The tool has been evaluated on a test dataset and obtained 76.6% ac-curacy, i.e. the system identified the right value of the three attributes in 76.6% of the events. This system will be integrated in the TextPro tool suite (Pianta et al., 2008).