@article{JOHNSON2001138,
    Abstract = {We generalize the concept of tree-width to directed graphs and prove that every directed graph with no ``haven'' of large order has small tree-width. Conversely, a digraph with a large haven has large tree-width. We also show that the Hamilton cycle problem and other NP-hard problems can be solved in polynomial time when restricted to digraphs of bounded tree-width.},
    Author = {Johnson, Thor and Robertson, Neil and Seymour, P.D. and Thomas, Robin},
    File = {Directed Tree-Width - 1-s2.0-S0095895600920318-main.pdf},
    ISSN = {0095-8956},
    Journal = {Journal of Combinatorial Theory, Series B},
    Number = {1},
    Pages = {138-154},
    Title = {Directed Tree-Width},
    URL = {https://www.sciencedirect.com/science/article/pii/S0095895600920318},
    Volume = {82},
    Year = {2001},
    bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0095895600920318},
    bdsk-url-2 = {https://doi.org/10.1006/jctb.2000.2031},
    date-added = {2021-07-26 16:51:37 +0200},
    date-modified = {2021-07-26 16:51:37 +0200},
    doi = {10.1006/jctb.2000.2031}
}

@article{JOHNSON2001138, Abstract = {We generalize the concept of tree-width to directed graphs and prove that every directed graph with no ``haven'' of large order has small tree-width. Conversely, a digraph with a large haven has large tree-width. We also show that the Hamilton cycle problem and other NP-hard problems can be solved in polynomial time when restricted to digraphs of bounded tree-width.}, Author = {Johnson, Thor and Robertson, Neil and Seymour, P.D. and Thomas, Robin}, File = {Directed Tree-Width - 1-s2.0-S0095895600920318-main.pdf}, ISSN = {0095-8956}, Journal = {Journal of Combinatorial Theory, Series B}, Number = {1}, Pages = {138-154}, Title = {Directed Tree-Width}, URL = {https://www.sciencedirect.com/science/article/pii/S0095895600920318}, Volume = {82}, Year = {2001}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0095895600920318}, bdsk-url-2 = {https://doi.org/10.1006/jctb.2000.2031}, date-added = {2021-07-26 16:51:37 +0200}, date-modified = {2021-07-26 16:51:37 +0200}, doi = {10.1006/jctb.2000.2031} }