1 citations · 1 across the 7 of their papers we have counts for
9 papers
Fairness in Graph-Theoretical Optimization Problems
Christopher Hojny, Frits Spieksma, Sten Wessel
There is arbitrariness in optimum solutions of graph-theoretic problems that can give rise to unfairness. Incorporating fairness in such problems, however, can be done in multiple…
Handling Sub-symmetry in Integer Programming using Activation Handlers
Christopher Hojny, Tom Verhoeff, Sten Wessel
Symmetry in integer programs (IPs) can be exploited in order to reduce solving times. Usually only symmetries of the original IP are handled, but new symmetries may arise at some n…
Integer Programming Models for Round Robin Tournaments
Jasper van Doornmalen, Christopher Hojny, Roel Lambers +1
Round robin tournaments are omnipresent in sport competitions and beyond. We propose two new integer programming formulations for scheduling a round robin tournament, one of which…
A flow-based formulation for parallel machine scheduling using decision diagrams
Daniel Kowalczyk, Roel Leus, Christopher Hojny +1
We present a new flow-based formulation for identical parallel machine scheduling with a regular objective function and without idle time. The formulation is constructed with the h…
Efficient MIP Techniques for Computing the Relaxation Complexity
Gennadiy Averkov, Christopher Hojny, Matthias Schymura
The relaxation complexity rc(X) of the set of integer points X contained in a polyhedron is the minimal number of inequalities needed to formulate a linear optimization problem ove…
Efficient Propagation Techniques for Handling Cyclic Symmetries in Binary Programs
Jasper van Doornmalen, Christopher Hojny
The presence of symmetries of binary programs typically degrade the performance of branch-and-bound solvers. In this article, we derive efficient variable fixing algorithms to disc…