Multiply Balanced Edge Colorings of Multigraphs

TL;DR

This paper proves a general theorem on balanced edge colorings of multigraphs, extending existing results and addressing complex amalgamation and disentangling problems with applications to Hamilton decompositions.

Contribution

It introduces a broad theorem that generalizes previous amalgamation results, allowing for more complex graph structures and addressing multiple notions of balance.

Findings

Generalized amalgamation theorem for multigraphs

Corollary on Hamilton decompositions of specific graph families

Addresses connectivity and fairness in edge colorings

Abstract

In this paper, a theorem is proved that generalizes several existing amalgamation results in various ways. The main aim is to disentangle a given edge-colored amalgamated graph so that the result is a graph in which the edges are shared out among the vertices in ways that are fair with respect to several notions of balance (such as between pairs of vertices, degrees of vertices in the both graph and in each color class, etc). The connectivity of color classes is also addressed. Most results in the literature on amalgamations focus on the disentangling of amalgamated complete graphs and complete multipartite graphs. Many such results follow as immediate corollaries to the main result in this paper, which addresses amalgamations of graphs in general, allowing for example the final graph to have multiple edges. A new corollary of the main theorem is the settling of the existence of Hamilton decompositions of the family of graphs $K(a_1,\dots, a_p;\lambda_1, \lambda_2)$; such graphs arose naturally in statistical settings.