Divendres 25 d'abril: Miguel Ballesteros - Going to the Roots of Dependency Parsing
Xavier Lluís
Hola!
Us informem que el proper divendres 25 d'abril tenim programat un seminari del TALP a càrrec de Miguel Ballesteros, a l'aula S208 de l'Edifici Omega del Campus Nord de la UPC.
L'hora d'inici del seminari seran les 11:00.
Aquests són els detalls del seminari:
| Títol | Going to the Roots of Dependency Parsing |
|---|---|
| Ponent | Miguel Ballesteros |
| Lloc | Omega-S208 Campus Nord - UPC |
| Dia | 25 Abril 2014 |
| Horari | 11:00h - Presentació |
| Abstract |
In this seminar I will first introduce transition-based dependency parsing and present the conclusions extracted from a journal paper that I have never had the chance to present in public, besides I'm going to sum up my current, past and future research collaboration projects with some new results and developments. Dependency trees used in syntactic parsing often include a root node representing a dummy word prefixed or suffixed to the sentence, a device that is generally considered a mere technical convenience and is tacitly assumed to have no impact on empirical results. We demonstrate that this assumption is false and that the accuracy of data-driven dependency parsers can in fact be sensitive to the existence and placement of the dummy root node. In particular, we show that a greedy, left-to-right, arc-eager transition-based parser consistently performs worse when the dummy root node is placed at the beginning of the sentence (following the current convention in data-driven dependency parsing) than when it is placed at the end or omitted completely. Control experiments with an arc-standard transition-based parser and an arc-factored graph- based parser reveal no consistent preferences but nevertheless exhibit considerable variation in results depending on root placement. We conclude that the treatment of dummy root nodes in data-driven dependency parsing is an underestimated source of variation in experiments and may also be a parameter worth tuning for some parsers. |
Us recordem que tota la informació dels propers seminaris i dels seminaris passats (incloses les transparències), la podeu trobar a la web dels seminaris del TALP.
Fins aviat!
Pranava i Xavi