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1. jll29 · 1790067648 · focus · HN ↗

   Yes: you can classify a test file by topic with gzip as follows:

     gzip -9 sports.txt   testfile.txt
   
     gzip -9 politics.txt testfile.txt
   
     gzip -9 business.txt testfile.txt
   

   (ass. sports.txt politics.txt and business.txt are text docs pertaining from the sports, politics and business domains, respectively, and have equal size)

   The test file belongs to the topic with the smallest size *.gz file.

   Witten's group at Waikato uni were perhaps the first to work on this.

   Also check out the Hutter prize if you are interested in this.

   1. myrmidon · 1790084526 · focus · HN ↗

      Nitpick: Doing it exactly like this is flawed because you let the compressibility of your references taint the result; what you would prefer is the compressed size of testfile given sports.txt/... as a dictionary without accounting for the compressed size of that, no?

      Really interesting approach though.

      1. [deleted] · 1790136237 · focus · HN ↗

         [deleted]

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