336 Chapter 12 Natural laNguage INterfaCe: QuestIoN aNswerINg system
Most of the empirical NLP methods employ statistical techniques, such
as n-gram models, hidden Markov models (HMMs), and probabilistic con-
text-free grammars (PCFGs). Given the successes of empirical NLP meth-
ods, researchers have begun to apply learning methods to the construction of
information extraction systems (McCarthy, 1995; Soderland, 1995). Several
different symbolic and statistical methods have been employed, but most of
them are used to generate one part of a larger information extraction system.
Majumder (2002) experimented with n-gram-based language modeling and
claimed to develop a language-independent approach to IR and natural lan-
guage processing.
12.4.3 ...