@article{COOPER2012414,
    Abstract = {This paper considers the problem of showing that every pair of binary trees with the same number of leaves parses a common word under a certain simple grammar. We enumerate the common parse words for several infinite families of tree pairs and discuss several ways to reduce the problem of finding a parse word for a pair of trees to that for a smaller pair. The statement that every pair of trees has a common parse word is equivalent to the statement that every planar graph is four-colorable, so the results are a step toward a language theoretic proof of the four color theorem.},
    Author = {Cooper, Bobbe and Rowland, Eric and Zeilberger, Doron},
    File = {Toward a language theoretic proof of the four color theorem - 1-s2.0-S0196885811001114-main - a.pdf},
    ISSN = {0196-8858},
    Journal = {Advances in Applied Mathematics},
    Keywords = {Four color theorem, Parse words},
    Number = {2},
    Pages = {414-431},
    Title = {Toward a language theoretic proof of the four color theorem},
    URL = {https://www.sciencedirect.com/science/article/pii/S0196885811001114},
    Volume = {48},
    Year = {2012},
    bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0196885811001114},
    bdsk-url-2 = {https://doi.org/10.1016/j.aam.2011.11.002},
    date-added = {2023-02-26 08:13:10 +0100},
    date-modified = {2023-02-26 08:13:10 +0100},
    doi = {10.1016/j.aam.2011.11.002}
}

@article{COOPER2012414, Abstract = {This paper considers the problem of showing that every pair of binary trees with the same number of leaves parses a common word under a certain simple grammar. We enumerate the common parse words for several infinite families of tree pairs and discuss several ways to reduce the problem of finding a parse word for a pair of trees to that for a smaller pair. The statement that every pair of trees has a common parse word is equivalent to the statement that every planar graph is four-colorable, so the results are a step toward a language theoretic proof of the four color theorem.}, Author = {Cooper, Bobbe and Rowland, Eric and Zeilberger, Doron}, File = {Toward a language theoretic proof of the four color theorem - 1-s2.0-S0196885811001114-main - a.pdf}, ISSN = {0196-8858}, Journal = {Advances in Applied Mathematics}, Keywords = {Four color theorem, Parse words}, Number = {2}, Pages = {414-431}, Title = {Toward a language theoretic proof of the four color theorem}, URL = {https://www.sciencedirect.com/science/article/pii/S0196885811001114}, Volume = {48}, Year = {2012}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0196885811001114}, bdsk-url-2 = {https://doi.org/10.1016/j.aam.2011.11.002}, date-added = {2023-02-26 08:13:10 +0100}, date-modified = {2023-02-26 08:13:10 +0100}, doi = {10.1016/j.aam.2011.11.002} }