A decomposition of Gallai multigraphs

Generalization of the Erdos-Gallai Inequality

P. Erdős and T. Gallai gave necessary and sufficient conditions for a sequence of non-negative integers to be graphic. Here,their result is generalized to multigraphs with a specified multiplicity. This both generalizes and provides a new proof of a result in the literature by Chungphaisan [2].

Density of Gallai Multigraphs

Diwan and Mubayi asked how many edges of each color could be included in a 3-edge-colored multigraph containing no rainbow triangle. We answer this question under the modest assumption that the multigraphs in question contain at least one edge between every pair of vertices. We also conjecture that this assumption is, in fact, without loss of generality.

A survey of the studies on Gallai and anti-Gallai graphs

The Gallai graph and the anti-Gallai graph of a graph G are edge disjoint spanning subgraphs of the line graph L(G). The vertices in the Gallai graph are adjacent if two of the end vertices of the corresponding edges in G coincide and the other two end vertices are nonadjacent in G. The anti-Gallai graph of G is the complement of its Gallai graph in L(G). Attributed to Gallai (1967), the study ...

Decomposing Semi-complete Multigraphs and Directed Graphs into Paths of Length Two

A P3-decomposition of a graph is a partition of the edges of the graph into paths of length two. We give a necessary and sufficient condition for a semi-complete multigraph, that is a multigraph with at least one edge between each pair of vertices, to have a P3-decomposition. We show that this condition can be tested in strongly polynomial-time, and that the same condition applies to a larger c...

The Gallai-Edmonds Decomposition for the k-Piece Packing Problem