Christopher Hojny



TU Darmstadt
Fachbereich Mathematik, AG Optimierung
Dolivostraße 15, 64293 Darmstadt (Germany)

Please find my new homepage at

Office Hour:

Monday, 13:00 - 14:00.

Research Interest:

  • Symmetry in Integer Programs
  • Graph Coloring Problems
  • Knapsack Polytopes
  • Polyhedral Treatment of Combinatorial Optimization Problems


  • Polytopes Associated with Symmetry Handling, with Marc E. Pfetsch, Mathematical Programming, 2018, DOI: 10.1007/s10107-018-1239-7.
    An online supplement with detailed results is available.
  • The SCIP Optimization Suite 5.0, with Ambros Gleixner, Leon Eifler, Tristan Gally, Gerald Gamrath, Patrick Gemander, Robert Lion Gottwald, Gregor Hendel, Thorsten Koch, Matthias Miltenberger, Benjamin Müller, Marc E. Pfetsch, Christian Puchert, Daniel Rehfeldt, Franziska Schlösser, Felipe Serrano, Yuji Shinano, Jan Merlin Viernickel, Stefan Vigerske, Dieter Weninger, Jonas T. Witt, and Jakob Witzig, available at kobv, 2017
  • Extended Formulations for Column Constrained Orbitopes, with Marc E. Pfetsch and Andreas Schmitt, preprint available at Optimization Online, 2017. (accepted for publication in Operations Research proceedings 2018)
  • On the Size of Integer Programs with Bounded Coefficients and Sparse Constraints, with Hendrik Lüthen and Marc E. Pfetsch, preprint available at Optimization Online, 2017.
  • Packing, Partitioning, and Covering Symresacks, preprint available at Optimization Online, 2017.
  • A Polyhedral Investigation of Star Colorings, with Marc E. Pfetsch, Discrete Applied Mathematics, 2016, 208, 59-78, DOI: 10.1016/j.dam.2016.03.003


  • Aussois COW 2018, Aussois, France, January 12, 2018:
    Symmetry Breaking Polytopes: A Framwork for Symmetry Handling in Binary Programs, slides
  • OR 2017, Berlin, Germany, September 8, 2017 (invited talk):
    Polyhedral Symmetry Handling Techniques Exploiting Problem Information
  • FRICO 2017, Trier, Germany, August 16, 2017:
    On the Size of Integer Programs with Bounded Coefficients or Sparse Constraints
  • ICMS 2016, Berlin, Germany, July 14, 2016:
    Symmetry Handling in Binary Programs via Polyhedral Methods
  • Aussois COW 2016, Aussois, France, January 5, 2016:
    Polytopes Associated with Symmetry Handling, slides
  • ISMP 2015, Pittsburgh, PA, July 15, 2015 (invited talk):
    Polyhedral Symmetry Handling via Fundamental Domains
  • CTW 2015, Marmara University Istanbul, May 26, 2015:
    Symmetry Handling via Symmetry Breaking Polytopes
  • FRICO 2014, Otto von Guericke Universität Magdeburg, July 30, 2014:
    Polyhedral description of star colorings

Poster Presentations

  • MIP 2017, HEC Montréal, Canada, June 19, 2017:
    Constrained Symresacks - Symmetry Handling Exploiting Packing, Partitioning, and Covering Constraints, poster
  • MIP 2016, University of Miami, Coral Gables, FL, May 23, 2016:
    Symmetry Handling via {0,±1}-Inequalities, poster

Teaching Assistance:

  • summer term 2018: Diskrete Optimierung (Prof. Dr. M. Pfetsch)
  • winter term 2017/18: Diskrete Mathematik (Prof. Dr. M. Pfetsch)
  • summer term 2017: Diskrete Optimierung (Prof. Dr. Y. Disser)
  • winter term 2016/17: Diskrete Mathematik (Prof. Dr. M. Pfetsch)
  • summer term 2016: Algorithmic Discrete Mathematics (PD Dr. A. Paffenholz)
  • winter term 2015/16: Einführung in die mathematische Software (PD Dr. A. Paffenholz)
  • summer term 2015: Algorithmic Discrete Mathematics (Prof. Dr. M. Pfetsch)
  • winter term 2014/15: Einführung in die mathematische Software (Dr. A. Paffenholz)
  • summer term 2014: Linear Algebra II (Prof. Dr. M. Otto)

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