The knapsack problem is one of the simplest and most fundamental NP-hard problems in
combinatorial optimization. We consider two knapsack problems which contain additional …

Undirected co-graphs are those graphs which can be generated from the single vertex
graph by disjoint union and join operations. Co-graphs are exactly the P_4 P 4-free graphs …

In this paper we consider the digraph width measures directed path-width, directed tree-
width, directed feedback vertex set number, directed feedback arc set number, cycle rank …

Graph coloring is an assignment of labels, so-called colors, to the objects of a graph subject
to certain constraints. The coloring problem on undirected graphs has been well studied, as …

An acyclic r-coloring of a directed graph G=(V, E) is a partition of the vertex set V into r
acyclic sets. The dichromatic number of a directed graph G is the smallest r such that G …

In this article we consider the Directed Steiner Path Cover problem on directed co-graphs.
Given a directed graph G=(V, E) G=(V, E) and a set T ⊆ VT⊆ V of so-called terminal …

In this paper we consider special subclasses of directed co-graphs and their
characterizations. The class of directed co-graphs has been well-studied by now and there …

The subset sum problem is one of the simplest and most fundamental NP-hard problems in
combinatorial optimization. We consider two extensions of this problem: The subset sum …

An oriented r-coloring of an oriented graph G corresponds to an oriented graph H on r
vertices, such that there exists a homomorphism from G to H. The problem of deciding …

In this paper we study the oriented vertex and arc coloring problem on edge series-parallel
digraphs (esp-digraphs) which are related to the well known series-parallel graphs. Series …