Stephan Held

Stephan Held is a Professor at the Research Institute for Discrete Mathematics, University of Bonn, where he conducts research and teaches in combinatorial optimization, VLSI design, and discrete algorithms. He holds a Ph.D. from the University of Bonn and has been actively publishing in top venues such as DAC, DATE, IPCO, and IEEE Transactions. His research spans theoretical and applied aspects of optimization in chip design and logistics. He leads significant academic initiatives, including serving as General Chair for ISPD 2026 and as an Associate Editor for Discrete Optimization.

Research Interests:

• VLSI Design: Clock scheduling, gate sizing, threshold voltage optimization, timing-driven placement and routing, repeater trees.
• Graph Coloring: Development of exactcolors, a high-performance open-source solver for maximum-weight stable set and graph coloring.
• Vehicle Routing: Work on time-dependent travel times, real-world benchmark creation using OpenStreetMap and Uber data, and winning the Amazon Last Mile Routing Challenge in 2021 with William Cook and Keld Helsgaun.

His recent publications focus on approximation algorithms for Steiner tree variants, cost-distance optimization in routing, and combinatorial methods in chip design. These works frequently appear in journals like Mathematical Programming, Discrete Optimization, and IEEE Transactions on CAD, as well as conferences including DAC, ISPD, and IPCO. The research combines theoretical rigor with practical applications in electronic design automation and transportation logistics.

Scientific Awards:

• Best Paper Award, DAC 2018
• Best Paper Award, DATE 2009

Prof. Held advises students and has contributed to the academic community through teaching and organizing conferences. He has taught courses on chip design, combinatorial optimization, integer programming, and algorithmic mathematics. He has organized major events such as the International Symposium on Physical Design (ISPD), the Hausdorff Summer School, and the IPCO conference. His lab and research group at the University of Bonn are deeply integrated into the Bonn International Graduate School in Mathematics (BIGS), fostering collaboration in computational combinatorial optimization.