C4.5 is a software extension of the basic ID3 algorithm designed by Quinlan to address the following issues not dealt with by ID3:

It is installed for use on Grendel (, but it may be set up on a local machine as follows:

C4.5 Release 8 Installation Instructions for UNIX

  1. Download the C4.5 source code.
  2. Decompress the archive:
    1. Type "tar xvzf c4.5r8.tar" (not universally supported), or, alternatively,
    2. Type "gunzip c4.5r8.tar.gz" to decompress the gzip archive, and then
      Type "tar xvf c4.5r8.tar" to decompress the tar archive.
  3. Change to ./R8/Src
  4. Type "make all" to compile the executables.
  5. Put the executables into a "bin" subdirectory and include it in the path for command-line usage.

Manual Pages


Click on the links below for examples of C4.5 usage: