- Two main approaches to NLP:
- language-based approach Speech and Language Processing
- probability and statistics-based approach (Foundations of Statistical Natural Language Processing).
- good tools for doing lexical analysis / parsing / tokenizing / text transformations.
- two excellent NLP classes on Coursera
In order to learn NLP, the first step is to get a through grounding in the basics of probability, and then from there look up new topics as the come up in the NLP book.
One of the things you will definitely need is good knowledge in the formal language area (automata, context-free grammar, context-sensitive grammars) .