Answering Portuguese Questions

Abstract

Abstract. Esfinge is a general domain Portuguese question answering system that participated in the last four editions of CLEF. This system uses the Web as a fundamental resource in its architecture, using information redundancy rather than sophisticated annotations of the document collections to retrieve answers. In this paper we describe experiments that took as starting point the version of Esfinge that participated at the evaluation contest CLEF 2007. These experiments consisted in using different types of search patterns to retrieve relevant documents for questions, as this issue (document retrieval) was responsible for most of the errors occurred at CLEF 2007. Keywords: Question answering, Portuguese, question reformulation Architecture of EsfingeIn this paper we will give a short description of the Portuguese question answering system Esfinge [1], as well as of a set of experiments performed with this system using different types of search patterns to retrieve relevant documents to answer questions.The architecture of Esfinge is composed by a pipeline of modules that handles each question in order to provide one answer.The questions are initially fed to an Anaphor Resolution module which caters for the resolution of anaphors. This module adds, to the original question, a list of alternative questions where the anaphors are (hopefully) resolved. Then, Esfinge iterates over the set of alternative questions created in the previous module:• The Question Reformulation module transforms the question into patterns of plausible answers. This is done using two different approaches: a) using a set of pre-defined pattern pairs that associate patterns of questions with patterns of plausible answers, producing a set of pairs (answer pattern, score) or b) using PALAVRAS [2] analysis to identify the main verb, its arguments and adjuncts and some entities from previous topic questions which are used to create search patterns.• The Search Document Collections module then uses these patterns to search in document collections. If no documents are retrieved, execution stops and NIL is returned meaning that the system is not able to answer the question.