Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
420418 | Discrete Applied Mathematics | 2009 | 4 Pages |
Abstract
Suppose that DD is an acyclic orientation of a graph GG. An arc of DD is dependent if its reversal creates a directed cycle. Let dmin(G) (dmax(G)) denote the minimum (maximum) of the number of dependent arcs over all acyclic orientations of GG. We call GGfully orientable if GG has an acyclic orientation with exactly dd dependent arcs for every dd satisfying dmin(G)⩽d⩽dmax(G). We show that a connected graph GG is fully orientable if dmin(G)⩽1. This generalizes the main result in Fisher et al. [D.C. Fisher, K. Fraughnaugh, L. Langley, D.B. West, The number of dependent arcs in an acyclic orientation, J. Combin. Theory Ser. B 71 (1997) 73–78].
Related Topics
Physical Sciences and Engineering
Computer Science
Computational Theory and Mathematics
Authors
Hsin-Hao Lai, Ko-Wei Lih, Li-Da Tong,