This is a guide to the material contained in http://www.math.gatech.edu/~thomas/OLDFTP/four/, an exact copy of the files formerly located on a now defunct anonymous ftp server. It falls naturally into two parts, Reducibility and Discharging. Common to both parts is the file unavoidable.conf, a list of the 633 unavoidable configurations stored in the following format: Vertices 1,...,r are the ring vertices (in order), and so the configuration itself consists of vertices r + 1, r + 2, ... n . The set is also available in a pictorial version.

Reducibility:

All of the above are now available at arXiv:1401.6481.

Discharging:

All of the above are now available at arXiv:1401.6485.