Alan Ritter, Stephen Soderland, Oren EtzioniTuring Center
Can a system that "learns from reading" figure out on it's own the semantic classes of arbitrary noun phrases? This is essential for text understanding, given the limited coverage of proper nouns in lexical resources such as WordNet. Previous methods that use lexical patterns to discover hypernyms suffer from limited precision and recall. We present methods based on lexical patterns that find hypernyms of arbitrary noun phrases with high precision. This more than doubles the recall of proper noun hypernyms provided by WordNet at a modest cost to precision. We also present a novel method using a Hidden Markov Model (HMM) to extend recall further.