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Stephen Choularton Honours Student 2002 31401937 Comp 449 14 June 2002 An Essay Language Modeling: A detailed look at stochastic language models and alternatives Section Page 1 Introduction 1 2 Non-stochastic Models 2 3 Stochastic Models 2 4 Tri-grams 2 5 The Search Problem 3 6 Organizing the Search Space 3 7 Reducing the Search Space 4 8 Where from here? 4 9 Conclusions 4 10 References 6 1 Introduction This essay is written to provide a detailed look at stochastic language models and alternatives. Firstly I intend to explain the problem language models seek to solve in the field of speech recognition then to outline the various approaches taken. Before I do this I should mention that prior to the language model becoming useful, a speech recognizer will already have endeavored to identify the phonemes (atomic sound units) present in an utterance. It will most likely have done this by matching them against Gaussian models of sound contained in Hidden Markov Models (HMMs) (see [Cassidy, 2002] at pages 63 to 68 for a fuller explanation of HMMs). Ever since [Baker, 1975] first proposed the use of network representations for