Characterizing Sparse Graphs by Map Decompositions

Ruth Haas1, Audrey Leet 2, Ileana Streinu3, Louis Theran2
1Mathematics Department, Smith College, Northampton, MA 01063.
2Department of Computer Science, University of Massachusetts, Amherst, MA 01003.
3Computer Science Department, Smith College, Northampton, MA 01063.

Abstract

A map is a graph that admits an orientation of its edges so that each vertex has out-degree exactly \(1\). We characterize graphs which admit a decomposition into \(k\) edge-disjoint maps after: (1) the addition of any \(\ell\) edges; (2) the addition of some \(\ell\) edges. These graphs are identified with classes of \emph{sparse} graphs; the results are also given in matroidal terms.