Every branch of mathematics employs some notion of a product that enables the com-
bination or decomposition of its elemental structures. In graph theory there are four main …

Contains a wealth of information previously scattered in research journals, conference
proceedings and technical reports. Identifies more than 200 unsolved problems. Every …

This is a book about graph homomorphisms. Graph theory is now an established discipline
but the study of graph homomorphisms has only recently begun to gain wide acceptance …

Aimed at graduate students and researchers, this fascinating text provides a comprehensive
study of the Erdős–Ko–Rado Theorem, with a focus on algebraic methods. The authors …

The circular chromatic number χ c (G) of a graph G (also known as 'the star-chromatic
number'), is a natural generalization of the chromatic number of a graph. In this paper, we …

The study of circular chromatic number Xc (G) of a graph G, which is a refinement of its
chromatic number, has been very active in the past decade. Many nice results are obtained …

The main theorem of this paper provides partial results on some major open problems in
graph theory, such as Tutteʼs 3-flow conjecture (from the 1970s) that every 4-edge …

This paper is the first part of an introduction to the subject of graph homomorphism in the
mixed form of a course and a survey. We give the basic definitions, examples and uses of …

The vertex‐labeling of graphs with nonnegative integers provides a natural setting in which
to study problems of radio channel assignment. Vertices correspond to transmitter locations …

We introduce the circular chromatic number χc of a digraph and establish various basic
results. They show that the coloring theory for digraphs is similar to the coloring theory for …