Suchergebnisse

This thesis is focused on temporal information processing, which is a task framed in the field of natural language processing. The aim of this task is to obtain the temporal location and ordering of the events expressed in text or discourse, which requires the automatic interpretation of temporal expressions, events, and the temporal relations between them. The majority of current approaches are based on morphosyntactic knowledge. However, temporal entities are often ambiguous at that language analysis level. Our hypothesis is that the linguistic expression of time is a semantic phenomenon and therefore, to achieve a better extraction performance, temporal information must be processed using semantics. To prove this hypothesis, we present a semantic approach to temporal information processing: TIPSem. This is an automated system that includes features based on lexical semantics, semantic roles, and temporal semantics, in addition to morphosyntactic features. TIPSem has been empirically evaluated through the participation in the TempEval-2 international evaluation exercise and subsequent experiments based on this test. The results obtained firmly support the presented hypothesis and their analysis demonstrates that semantic features aid in handling morphosyntactic ambiguity and favour generalization capabilities. These conclusions have been reached for different languages (i.e., English, Spanish, Italian, and Chinese), which supports the defended hypothesis at a multilingual level. Finally, as compared with the state of the art, TIPSem obtains a very competitive performance level and introduces a remarkable improvement in event processing. TIPSem has been applied to the problem of graphical representation of temporal information. We have developed a dynamic interface which brings users time-based access to information: Time-Surfer. The results obtained through a user-oriented evaluation of this interface demonstrate that TIPSem's performance is also satisfactory from an extrinsic standpoint. ; This PhD thesis has been supported by the Spanish Government, in projects: TIN-2006-15265-C06-01, TIN-2009-13391-C04-01 and PROMETEO/2009/119, where Hector Llorens is funded under a FPI grant (BES-2007-16256).

L'experiment T2K, una col·laboració internacional on participen més de 500 físics de 12 països, ha detectat l'aparició de neutrins electrònics a partir d'un feix de neutrins muònics. És la primera vegada que s'observa aquest fenomen, conegut com a "oscil·lació", entre aquest tipus de neutrins, la qual cosa suposa un important pas per entendre millor aquesta partícula elemental. A més, aquesta detecció obre la porta a l'estudi experimental d'un dels principals misteris de l'Univers: el domini de la matèria enfront de l'antimatèria. En l'experiment participen investigadors de l'Institut de Física d'Altes Energies (IFAE, consorci Generalitat de Catalunya-Universitat Autònoma de Barcelona) i de l'Institut de Física Corpuscular (IFIC, CSIC-Universitat de València). ; El experimento T2K, una colaboración internacional donde participan más de 500 físicos de 12 países, ha detectado la aparición de neutrinos electrónicos a partir de un haz de neutrinos muónicos. Es la primera vez que se observa este fenómeno, conocido como "oscilación", entre este tipo de neutrinos, lo que supone un importante paso para entender mejor esta partícula elemental. Además, esta detección abre la puerta al estudio experimental de uno de los principales misterios del Universo: el dominio de la materia frente a la antimateria. En el experimento participan investigadores del Institut de Física d'Altes Energies (IFAE, consorcio Generalitat de Catalunya-Universitat Autònoma de Barcelona) y del Institut de Física Corpuscular (IFIC, CSIC-Universitat de València). ; The T2K experiment, an international collaboration with over 500 physicists from 12 different countries, has detected the appearance of electron neutrinos in a muon neutrino beam. It is the first time researchers observe this phenomenon - known as "oscillation" - in these types of neutrinos. The discovery could represent an important step towards a clearer understanding of this elementary particle. Having detected the presence of these types of neutrinos opens the door to an experimental study of one of the greatest mysteries of the Universe: the power of matter over antimatter. The experiment includes participation of researchers from the Institute of High Energy Physics (IFAE, consortium formed by the Government of Catalonia-Universitat Autònoma de Barcelona) and from the Institute of Corpuscular Physics (IFIC, CSIC- Universitat de València).