W. Hochstättler, R. Nickel, P. Oertel, Lehrgebiet Mathematik, W. Hochstättler, R. Nickel, ...
We describe a new solution approach for order sequencing which reflects the build-to-order strategy of the European automobile industry. Therefore, it has to cope with a variety of customer orders...
Matroid Polytopes On the Flow Lattice of Uniform Oriented (2008)
Grundlagen Der Informatik, Winfried Hochstättler, Robert Nickel, W. Hochstättler, ...
Recently Hochstättler and Neˇsetˇril introduced the flow lattice of an oriented matroid as generalization of the lattice of all integer flows of a digraph or more general a regular matroid. This...
Complexity results on restricted instances of a paint shop problem for words (2006)
Bonsma, P.S., Epping, Th., Hochstättler, W.
We study the following problem: an instance is a word with every letter occurring twice. A solution is a 2-coloring of its letters such that the two occurrences of every letter are colored with...
Online matching on a line (2003)
Fuchs, B., Hochstättler, W., Kern, W.
We prove a lower bound $\rho \geq 9.001$ for the competitive ratio of the so-called online matching problem on a line. As a consequence, the online matching problem is revealed to be strictly more...
Note on the game chromatic index of trees (2002)
Erdös, P.L., Faigle, U., Hochstättler, W., Kern, W.
We study edge coloring games defining the so-called game chromatic index of a graph. It has been reported that the game chromatic index of trees with maximum degree $\Delta = 3$ is at most $\Delta +...
A Note on MaxFlow-MinCut and Homomorphic Equivalence in Matroids (1999)
W. Hochstättler, W. Hochstattler, J. Nesetril, J. Nesetril, Winfried Hochstattler, Jaroslav Nesetril
In this note we point out that the validity of the max-flow-min-cut theorem in a matroid port M is equivalent to the homomorphic equivalence of the dual port M to a circuit in the category of matroid...
Bases of Cocycle Lattices and Submatrices of a Hadamard Matrix (1998)
W. Hochstättler, M. Loebl, Zentrum Paralleles, Winfried Hochstattler, Martin Loebl
We study the lattice lat(M) of cocycles of a binary matroid M . By an isomorphism we show that such lattices are equivalent to lattices generated by the columns of proper submatrices of Sylvester...
Large Circuits in Binary Matroids of Large Cogirth: II (1998)
W. Hochstättler, B. Jackson, Winfried Hochstattler, Winfried Hochstattler, Bill Jackson, ...
Let F 7 denote the Fano matroid and M be a simple connected binary matroid such that every cocircuit of M has size at least d 3. We show that if M does not have an F 7 -minor, M 6= F 7 , and d = 2...
Using network-flow techniques to solve an optimization problem from surface-physics (1996)
Blasum, U., Hochstättler, W., Moll, C., Rieger, H.
The solid-on-solid model provides a commonly used framework for the description of surfaces. In the last years it has been extended in order to investigate the effect of defects in the bulk on the...
Farkas' Lemma and Morphism Duality (1996)
W. Hochstättler, W. Hochstattler, J. Nesetril, J. Nesetril, Winfried Hochstattler, Jaroslav Nesetril
In this paper we investigate the class NP " co-NP (or the class of problems permitting a good characterization) from the point of view of morphisms of oriented matroids. We prove several...
The Simulated Trading Heuristic for Solving Vehicle Routing Problems (1996)
A. Bachem, W. Hochstättler, M. Malich
We present an improvement heuristic for vehicle routing problems. The heuristic finds complex customer interchanges to improve an initial solution. Our approach is modular, thus it is easily adjusted...
A Pseudoconfiguration of Points without Adjoint (1995)
W. Hochstättler, W. Hochstattler, W. Hochstattler, S. Kromberg, S. Kromberg, S. Kromberg
We give an example of a simple oriented matroid D that admits an oriented adjoint. Already any adjoint of the underlying matroid D, however, does itself not admit an adjoint. D arises from the...
Oriented Matroids from Wild Spheres (1995)
W. Hochstättler, W. Hochstattler, W. Hochstattler
In a recent article [5] we gave a lattice-theoretical characterization of oriented matroids in terms of the zero-map. In this paper we derive from that characterization a generalization of one...
Adjoints and Duals of Matroids Linearly Representable over a Skewfield (1994)
Following an approach suggested by B. Lindstrom we prove that the dual of a matroid representable over a skewfield is itself representable over the same field. Along the same line we show that any...
Adjoints and Duals of Matroids Linearly Representable over a Skewfield (1994)
Following an approach suggested by B. Lindstrom we prove that the dual of a matroid representable over a skewfield is itself representable over the same field. Along the same line we show that any...
Computational Experience with General Equilibrium Problems (1993)
A. Volmer, A. Bachem, W. Hochstättler, B. Steckemetz
We report on computational experience with an implementation of three algorithms for the general economic equilibrium problem. As a result we get that the projection algorithm for variational...