This week we talked about parsing using hidden Markov models and context-free grammars. Below are some pointers to written introductions.

• Wikipedia explains Context-free grammars.

• Charniak’s textbook explains what hidden Markov models are in Section 3.2, what probabilistic context-free grammars in Section 5.1, why probabilistic context-free grammars generalize hidden Markov models in Section 6.1, and inference algorithms for these language models in Sections 4.1, 4.2, and 6.2.

I’m still working on a way for you to play with these models hands-on. Please stay tuned.

The context-sensitivity of Swiss German was proven in: Stuart M. Shieber. 1985. Evidence against the context-freeness of natural language. Linguistics and Philosophy 8:333-343.