This paper utilizes heuristic algorithms for determining graph thickness in order to attempt to find a 10-chromatic thickness-2 graph. Doing so would eliminate 9 colors as a potential solution to the Earth-moon Problem. An empirical analysis of the algorithms made by the author are provided. Additionally, the paper lists various graphs that may or nearly have a thickness of 2, which may be solutions if one can find two planar subgraphs that partition all of the graph’s edges.
Weaver, Robert C.
"Utilizing graph thickness heuristics on the Earth-moon Problem,"
Rose-Hulman Undergraduate Mathematics Journal: Vol. 24:
2, Article 5.
Available at: https://scholar.rose-hulman.edu/rhumj/vol24/iss2/5