norvig.com —
Peter Norvig (director of search quality at Google) details how to write a Spelling Corrector like Google uses in 21 lines of Python 2.5 code. He also has links to people who wrote versions in different programming languages like C#, PHP, Java and Javascript.
"The full details of an industrial-strength spell corrector like Google's would be more confusing than enlightening, but I figured that on the plane flight home, in less than a page of code, I could write a toy spelling corrector that achieves 80 or 90% accuracy at a processing speed of at least 10 words per second."
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