This repository contains some Natural Language Processing tools. 

1. Email extraction: extracts links present on the web pages by the use of efficient regular expressions.

2. Spelling auto correction:  
    Implements the following language models:
     • Laplace Unigram Language Model
     • Laplace Bigram Language Model
     • Stupid Backoff Language Model
     • Custom Language Model

3. Sentiment Analysis: trained a Naïve Bayes classifier on IMDB dataset for binary classification of movies.

4. Named Entity Recognition:  build a maximum entropy Markov model for identifying person names in newswire text.

5. Semantics:  written a probabilistic context free grammar for a small subset of English.

6. CKY Parsing Algorithm: build a probabilistic parser by implementing the CKY parser.

7. Information Retrieval: build an inverted index to quickly retrieve documents.