Sunday, December 13, 2009

Prediction by Partial Matching

I am currently working on a project for a natural language processing course. Given my interest in temporal pattern recognition, I decided to make the project about text prediction. For the last few weeks I have been really excited because I thought I discovered an innovative algorithm which was doing extremely well compared to existing methods. In particular, it completely outperforms my previous approaches using neural networks/HTM when it comes to almost any pattern recognition task. However, today I was disappointed to learn that almost exactly the same algorithm was discovered back in the 80s. It is a data compression algorithm called prediction by partial matching (PPM). PPM happens to be one of the best text compression algorithms, so at least its nice to know that I independently discovered it. However, I would have been much happier if I had been the first to do so.

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