February 19, 2010

The Noisy Channel Model for Unsupervised Word Sense Disambiguation

Deniz Yuret and Mehmet Ali Yatbaz. Computational Linguistics, Volume 36, Number 1, March 2010. (Abstract, PDF)

Abstract: We introduce a generative probabilistic model, the noisy channel model, for unsupervised word sense disambiguation. In our model, each context C is modeled as a distinct channel through which the speaker intends to transmit a particular meaning S using a possibly ambiguous word W. To reconstruct the intended meaning the hearer uses the distribution of possible meanings in the given context P(S|C) and possible words that can express each meaning P(W|S). We assume P(W|S) is independent of the context and estimate it using WordNet sense frequencies. The main problem of unsupervised WSD is estimating context dependent P(S|C) without access to any sense tagged text. We show one way to solve this problem using a statistical language model based on large amounts of untagged text. Our model uses coarse-grained semantic classes for S internally and we explore the effect of using different levels of granularity on WSD performance. The system outputs fine grained senses for evaluation and its performance on noun disambiguation is better than most previously reported unsupervised systems and close to the best supervised systems.

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