Cordian Benedikt Riener

Cordian Benedikt Riener is a Professor in Mathematics at UiT The Arctic University of Norway, Tromsø, and serves as Pro-Dean for PhD education at the Faculty of Science and Technology. He leads the Algebra group and is a co-director of the Lie-Størmer Center for Fundamental Structures in Computational and Pure Mathematics. His academic roles include chairing the Norwegian Mathematics Council and serving on the Abel Prize board.

• Habilitation in Mathematics (2018, University of Konstanz)
• Magister Artium in Philosophy (2013, Goethe University Frankfurt)
• PhD in Mathematics (2011, Goethe University Frankfurt)
• Master in Pure Mathematics (2005, Université de Bordeaux 1)
• Diplom in Mathematical Economics (2006, Universität Ulm)

Riener’s research bridges mathematics and theoretical computer science, focusing on computational complexity, real algebraic geometry, and polynomial optimization. His work includes characterizing positive polynomials via sums of squares, studying moment problems, and developing semidefinite relaxation methods. He explores symmetry in algebraic structures, such as Specht ideals and Weyl group orbits, with applications in discrete geometry and spectral graph theory. His recent publications emphasize symmetric semi-algebraic sets, trigonometric polynomial optimization, and tropical geometry.

The 15 most recent articles span 2023-2025, addressing topics like symmetric nonnegative forms, orbit space descriptions, and algorithmic symmetry reduction. Keywords include Real Algebraic Geometry, Optimization, and Computational Complexity, with subfields such as Sums of Squares, Spectral Bounds, and Tropical Geometry.

• Aalto Science Institute Fellow (2012-2016)
• Zukunftskolleg Associate Fellow (2011-2012)

Riener contributes to academic service as chair of the Norwegian Mathematics Council and Abel Prize board member. He has organized conferences like ISSAC 2023 and Nordic Combinatorial Conference 2022. His projects include POEMA (Horizon 2020) and SymRAG, with leadership in the Lie-Størmer Center and MASCOT collaborations.