A digraph D = (V,A) is arc-traceable if for each arc xy in A, xy lies on a directed path containing all the vertices of V, i.e., hamiltonian path. We prove a conjecture of Quintas [7]: if D is arc-traceable, then the condensation of D is a directed path. We show that the converse of this conjecture is false by providing an example of an upset tournament which is not arc-traceable. We then give a characterization for upset tournaments in terms of their score sequences, characterize which arcs of an upset tournament lie on a hamiltonian path, and deduce a characterization of arc-traceable upset tournaments.
@article{bwmeta1.element.bwnjournal-article-doi-10_7151_dmgt_1287, author = {Arthur H. Busch and Michael S. Jacobson and K. Brooks Reid}, title = {On a conjecture of quintas and arc-traceability in upset tournaments}, journal = {Discussiones Mathematicae Graph Theory}, volume = {25}, year = {2005}, pages = {225-239}, zbl = {1112.05045}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_7151_dmgt_1287} }
Arthur H. Busch; Michael S. Jacobson; K. Brooks Reid. On a conjecture of quintas and arc-traceability in upset tournaments. Discussiones Mathematicae Graph Theory, Tome 25 (2005) pp. 225-239. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_7151_dmgt_1287/
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