What are books about how to build a natural language parsing program like this:
input: I got to TALL you output: I got to TELL you input: Big RAT box output: Big RED box in: hoo un thum zend three out: one thousand three
It must have the language model that allows to predict what words are misspelled !
What are the best books on how to build such a tool??
p.s. Are there free webservices to spell-check? From Google maybe?..
Peter Norvig has written a terrific spell checker. Maybe that can help you.
In Dev Days London, Michael Sparks presented a Python script coded exactly for that. It was surprisingly very simple! See if you can find in Google. Maybe somebody here will have the link.
You have at least three options
You can write a program which understands the language (i.e. what a word means). This is a topic for research today. Expect the first results when you can buy a computer which is fast enough to run such a program (which is probably in 10 years when computers have become 1000 times faster than today).
Use a huge corpus (text documents) to train a Hidden Marcov Model.
Use a huge corpus and generate statistics about quadruplets n-grams, i.e. how often a tuple of N words appears. I don't have a link handy for this but the idea is that some words always appear in the context of other words. So when you parse your text into 4-grams and look them up in your database and you can't find one, chances are that there is something wrong with the current tuple. The next step is to find all possible matches (other 4-grams which have a small soundex or similar distance to the current one) and try the one with the highest frequency.
Google has this data for quite a few languages and you might find more in Google labs about this.
[EDIT] After some googling, I finally found the link: On this page, you can buy English 1- to 5-grams which Google collected over the whole Internet on 6 DVDs.
Googling for "google spelling statistics n-grams" will also turn up some interesting links.
There are quite a few Java libraries for natural language processing that would help you implement a spelling corrector. But you asked about a book. Foundations of Statistical Natural Language Processing by Christopher D. Manning and Hinrich Schütze looks like a good option. The first author is a Stanford Professor leading a group that does natural language processing and developing Java libraries and NLP resources that many people use.