This mathematica notebook implements a
routine which can be used to generate CNFs which encode the existence of
even edge colouring of a a graph with vertices of degrees 2 and 4. For a
further discussion see the acompanying paper.
The notebook and instances available here are free to use. Please include a citation to the paper if you found the instances useful.
The notebook uses some functions from GrafPack which can be found here
In this library you can find some examples generated with
the notebook above.
The examples are based on 4-regular cages. The satisifiable cases correspond
to the cages themselves and the unsatisfiable to the cages with one edge subdivided.
The index in the name of each file correspond to the girth of the cage.