A mixed hypergraph H = (X, C,D) consists of the vertex set X and two families of subsets: the family C of C-edges and the family D of D-edges. In a coloring, every C-edge has at least two vertices of common color, while every D-edge has at least two vertices of different colors. The largest (smallest) number of colors for which a coloring of a mixed hypergraph H using all the colors exists is c...

Kostochka, A.V., List edge chromatic number of graphs with large girth, Discrete Mathematics 101 (1992) 189-201. It is shown that the list edge chromatic number of any graph with maximal degree A and girth at least 8A(ln A + 1.1) is equal to A + 1 or to A.

We consider the following type of question: Given a partial proper d-edge coloring of the d-dimensional hypercube Qd, and lists of allowed colors for the non-colored edges of Qd, can we extend the partial coloring to a proper d-edge coloring using only colors from the lists? We prove that this question has a positive answer in the case when both the partial coloring and the color lists satisfy ...

In the minimum sum edge coloring problem, we aim to assign natural numbers to edges of a graph, so that adjacent edges receive different numbers, and the sum of the numbers assigned to the edges is minimum. The chromatic edge strength of a graph is the minimum number of colors required in a minimum sum edge coloring of this graph. We study the case of multicycles, defined as cycles with paralle...

A proper edge-coloring of a graph G is a mapping α : E(G)→ N such that α(e) 6= α(e′) for every pair of adjacent edges e, e′ ∈ E(G). A proper edge-coloring of a graph G is an interval coloring if the colors of edges incident to each vertex of G form an interval of integers. A graph G is interval colorable if it has an interval coloring. Since not all graphs admit an interval coloring, a measure ...

We consider the parameterised complexity of several list problems on graphs, with parameter treewidth or pathwidth. In particular, we show that List Edge Chromatic Number and List Total Chromatic Number are fixed parameter tractable, parameterised by treewidth, whereas List Hamilton Path is W[1]-hard, even parameterised by pathwidth. These results resolve two open questions of Fellows, Fomin, L...

B. Szegedy [Edge coloring models and reflection positivity, Journal of the American Mathematical Society 20 (2007) 969–988] showed that the number of homomorphisms into a weighted graph is equal to the partition function of a complex edge-coloring model. Using some results in geometric invariant theory, we characterize for which weighted graphs the edge-coloring model can be taken to be real va...