Chapter 13. Question Answering
Nico Schlaefer and Jennifer Chu-Carroll
13.1. Introduction and History
Question answering (QA) systems retrieve answers to user questions from information sources. In contrast to the keyword search paradigm adopted by most traditional information retrieval (IR) systems, QA systems can be asked questions in natural language, which is more intuitive and also more expressive than mere keywords. In addition, while IR systems return passages or documents in response to the user queries, QA systems attempt to provide answers that are accurate and to the point. Often, the web is utilized as a large, redundant, and up-to-date information source. However, local text corpora are frequently used for advanced search techniques ...