We consider Constrained Semi-Assignment Problems, where one has to optimally assign
discrete values to decision variables, and where furthermore logical constraints restrict the set …

Lattice matrices are 0/1-matrices used in the description of certain lattice polyhedra and
related to dicuts in a graph. The incidence matrix A I of a so-called intersection of two ring …

We reexamine the class of (0 , ±1 ) matrices called submodular, which we introduced in (Ann.
Discrete Math. 15 (1982) 189). Our key idea in this paper is to define, for each submodular …

A significant achievement in polyhedral combinatorics has been the proof of the perfect
graph theorem (Lovdsz [1972]). A major step thereof consisted in characterizing the notion of …

The validity of the two-phase method for preemptive scheduling is established in a wide
context by means of a classical result of polarity. A geometrical interpretation is given and …

Given two ring families C and D on a finite ground set V, with both ø and VϵC and D, consider
the family of so-called intersections L = [L ⊂- V¦L = C∩D, C ϵ C, D ϵ D and C∪D = V] …

This thesis studies the reconstruction and generation of oriented matroids. Oriented matroids
are a combinatorial abstraction of discrete geometric objects such as point configurations …

… Arlette Gaillard von demselben Institut danke ich für die zu Beginn der Arbeit geführten
Diskussionen, die mir halfen, den richtigen Weg einzuschlagen. …