Mirror bipartite graphs

TL;DR

This paper introduces the concept of mirror bipartite graphs, characterizes their degree sequences, and explores their applications in studying graphs with limited loops, revealing new structural insights.

Contribution

It provides a characterization of degree sequences of mirror bipartite graphs and demonstrates their utility in analyzing graphs with at most one loop per vertex.

Findings

Characterization of degree sequences for mirror bipartite graphs

Construction method for mirror bipartite graphs from degree sets

Application to degree sequences of graphs with limited loops

Abstract

Intuitively speaking, a bipartite graph is mirror if it can be drawn in the Cartesian plane in such a way that, the vertices of one stable are points in x=0, the vertices of the other stable set are points in x=1, the edges are straight line segments joining adjacent vertices and the resulting configuration is symmetric with respect to the line x=1/2. The concept of mirror bipartite graph appears naturally when studying certain types of products of graphs as for instance the Kronecker product. Motivated by this fact, we study mirror bipartite graphs from the point of view of their degree sequences and of their degree sets. We characterize the sequences of degrees of mirror bipartite graphs. We also show that from a given set P of positive integers, we can construct a bipartite graph of order 2max P, which is mirror. Furthermore, very little is known for the degree sequences of graphs with loops attached, when the number of loops attached is limited. We show in this paper that mirror bipartite graphs constitute a powerful tool to study the degree sequences of these graphs when the number of loops attached at each vertex is at most $1$.