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Tobias Metzlaff






LAAS-CNRS 
Équipe POP Office E53

 
7 Avenue du Colonel Roche 
31400 Toulouse, France 

Mail: math"at"tobiasmetzlaff"dot"com
Phone: (+33) 05 61 33 64 80

November: New Preprint on arXiv | February: SPP Workshop Announcement | March: Talk at JNCF



Research

My research statement is available here. I am a Mathematics postdoc in the POP team of LAAS-CNRS with Victor Magron and Igor Klep supported by COMPUTE. We develop and improve algorithms to solve computational problems through the exploitation of algebraic structures.

In particular, I am interested in crystallographic symmetries related to Weyl groups and weight lattices of Lie algebras, multiplicative invariants, generalized Chebyshev polynomials as well as applications in polynomial optimization and combinatorics. My favorite research project hides behind the images to the right.

Publications


    Exploiting Term Sparsity in Symmetry-Adapted Basis for Polynomial Optimization with Igor Klep, Victor Magron and Jie Wang, 2025 (arxiv, hal, preprint submitted)

    Additive and Multiplicative Coinvariant Spaces of Weyl Groups in the Light of Harmonics and Graded Transfer with Sebastian Debus, 2024 (arxiv, hal, published in J. Algebra)

    On symmetry adapted bases in trigonometric optimization, 2023 (arxiv, hal, published in J. Symb. Comput.)

    Symmetry Adapted Bases for Trigonometric Optimization, 2023 (published in ACM Commun. Comput. Algebra)

    Optimization of trigonometric polynomials with crystallographic symmetry and spectral bounds for set avoiding graphs with Evelyne Hubert, Philippe Moustrou and Cordian Riener, 2022 (arxiv, hal, published in Math. Program.)

    Orbit Spaces of Weyl Groups Acting on Compact Tori: A Unified and Explicit Polynomial Description with Evelyne Hubert and Cordian Riener, 2022 (arxiv, hal, published in SIAM J. Appl. Algebra Geom.)

    𝕋-Orbit Spaces of Multiplicative Actions and Applications with Evelyne Hubert, Philippe Moustrou and Cordian Riener, 2022 (published in ACM Commun. Comput. Algebra)

    Computing free non-commutative Gröbner Bases over with Singular:Letterplace with Viktor Levandovskyy and Karim Abou Zeid, 2020 (arxiv, hal, published in J. Symb. Comput.)

    Computation of free non-commutative Gröbner Bases over with Singular:Letterplace with Viktor Levandovskyy and Karim Abou Zeid at ISSAC, 2020 (hal, published in ACM Commun. Comput. Algebra)



Software


    TSSOS a Julia package for polynomial optimization with term and chordal sparsity (Contribution: symmetry reduction, benchmarks)

    GeneralizedChebyshev a Maple package for the irreducible reduced root systems and their associated generalized Chebyshev polynomials of the first kind (Contribution: 100%)

    Singular:Letterplace a Singular extension for finitely presented modules over finitely presented associative non-commutative algebras (Contribution: Gröbner Bases for noncommutative polynomials with coefficients in rings, benchmarks)



Posters


    Saarbrücken SFB-TRR 195 Annual Meeting 2023: Fundamental invariants of improper symplectic reflection groups with Ulrich Thiel

    ISSAC 2023: Symmetry Adapted Bases for Trigonometric Optimization

    ISSAC 2022: 𝕋-Orbit Spaces of Multiplicative Actions and Applications with Evelyne Hubert, Philippe Moustrou and Cordian Riener



Theses


    Crystallographic Groups and Chebyshev Polynomials in Global Optimization (PhD thesis with Evelyne Hubert at Université Côte d'Azur)

    Computational Improvements for Non-Commutative Gröbner Bases over /m (MSc thesis with Viktor Levandovskyy at RWTH Aachen University)

    Periodic Linear Discrete Systems and their Canonical Form (BSc thesis with Eva Zerz at RWTH Aachen University)



Talks


   JNCF 2026:  Exploiting Term Sparsity in Symmetry-Adapted Basis for Polynomial Optimization

   EUCCO 2025:  A Symmetric TSSOS Hierarchy for Polynomial Optimization

   ACA 2025:  Combining Sparsity and Symmetry for SOS-Certificates

   SPOT 96:  Symmetry in Trigonometric Optimization

   EURO 2024:  Spectral bounds for set avoiding graphs via polynomial optimization

   MoPAT 2024:  Chebyshev Moments

   JNCF 2024:  Singularités symplectiques et invariants diagonaux

   AROMATH Seminars 2023:  Symplectic singularities and diagonal invariants

   AG 2023:  Crystallographic Symmetries in Trigonometric Optimization

   JNCF 2023:  Optimisation Trigonométrique avec Symétrie

   Paris POEMA Workshop 2022:  Optimization of trigonometric polynomials with crystallographic symmetry and applications

   JNCF 2022:  Polynomial description for the 𝕋-Orbit Spaces of Multiplicative Actions

   Sophia Antipolis Industrial Workshop 2021:  Orbit Spaces for exponential Weyl Group Actions and the Chromatic Number of ℝn

   Modern Analysis Related to Root Systems with Applications 2021:  Regions of orthogonality of generalized Chebyshev polynomials as semi-algebraic set

   AROMATH Seminars 2021:  The Chromatic Number of ℝn via optimization of multivariate Chebyshev polynomials

   ICMS 2020:  Gröbner bases over 𝕂 and ℤ in theory and practice



Curriculum Vitae

My tabular CV is available here. I have studied Mathematics at RWTH Aachen University and conducted my doctorate at Centre Inria d'Université Côte d'Azur with Evelyne Hubert. As a member of the Marie Skłodowska-Curie Innovative Training Network POEMA, I have been elected representative of the network's fifteen early stage researchers. In December 2022, I defended my dissertation on Crystallographic Groups and Chebyshev Polynomials in Global Optimization. Afterwards, I joined the Algebra Group of University of Kaiserslautern-Landau as a postdoc with Ulrich Thiel and contributed to the DFG project SFB-TRR 195 and the research program SymbTools. Next to research and advanced algebra studies, I have participated in various teaching and dissemination activities. Following my interest in applying algebra to problems in optimization and combinatorics, I did a second postdoc within the POP team of LAAS-CNRS with Victor Magron and Igor Klep supported by COMPUTE. In Toulouse, I have specialized on optimization algorithms and algebraic structure exploitation.



Scientific Events


    2026:   JNCF (Luminy, FR)   


    2025:   TENORS Learning Week (Sophia Antipolis, FR)    SPOT Seminar (Toulouse, FR)    COMPUTE Kickoff Meeting (Saclay, FR)    ACA (Heraklion, GR)    EUCCO (Klagenfurt, AT)   

   
   (17 July 2025, Heraklion, GR, picture taken by the organizers)

   
   (8 Octobre 2025, Klagenfurt, AT, picture taken by Daniel Brosch)


    2024:   JNCF (Luminy, FR)    MoPAT (Konstanz, DE)    Arctic MSCA Symposium (Tromsø, NO)    EURO (Copenhagen, DK)   

   
   With Vu Trung Hieu, Ettore Turatti and Arne Lien (7 June 2024, Tromsø, NO, picture taken by Cordian Riener)

   
   With Ulrich Thiel, Erec Thorn, Liam Rogel, Tam Linke and Fabian Mäurer (28 Novembre 2024, Kaiserslautern, DE)


    2023:   JNCF (Luminy, FR)    Summer School on Processes and Heat Kernels with Symmetries (Angers, FR)    SIAM AG (Eindhoven, NL)    ISSAC (Tromsø, NO)    Summer School on Higher Structures in Algebra and Geometry (Nordfjordeid, NO)    Postdoc Appreciation Week Germany (online)    SFB-TRR 195 Annual Meeting (Saarbrücken, DE)    SingAlg (Kaiserslautern, DE)    Workshop on Symmetry, Stability, and interactions with Computation (Luminy, FR)   

   
   With Sven Polak and Arne Lien (18 November 2023, Parc National des Calanques, FR, picture taken by Sebastian Debus)


    2022:   Mørketidens Mattemøte (Tromsø)    POEMA Workshop (online)    JNCF (Luminy, FR)    Summer School on Real and Tropical Algebraic Geometry (Nordfjordeid, FR)    ISSAC (Lille, FR)    POEMA Workshop (Paris, FR)    Winter School on Computational Algebraic Geometry (Kaiserslautern, DE)   


    2021:   Mørketidens Mattemøte (Tromsø, NO)    POEMA Workshop (online)    General Julia Training (online)    Workshop on Algebraic Combinatorics of the Symmetric Groups and Coxeter Groups (Cetraro, IT)    POEMA Workshop (Toulouse, FR)    Workshop on Modern Analysis Related to Root Systems with Applications (Luminy, FR)    POEMA Industrial Workshop (Sophia Antipolis, FR)   


    2020:   POEMA Workshop (Florence, IT)    JNCF (Luminy, FR)    POEMA Learning Weeks (online)    SFO (online)    ICMS (Braunschweig, DE)    ISSAC (Kalamata, GR)    POEMA Workshop (online)   



Cycling Highlights


    2026:    Mont Ventoux (Provence, FR)

   
   Tom Simpson Memorial (10 April 2026, Provence, FR)


    2025:    Tourmalet (Pyrénées, FR)   Aubisque/Soulor (Pyrénées, FR)   200k (Landes de Gascogne, FR)   Port de Balès/Peyresoudre/Aspin (Pyrénées, FR)   Tourmalet 2 (Pyrénées, FR)

   
   Octave Lapize: "Le Géant du Tourmalet" (4 July 2025, Pyrénées, FR)


    2024:    Kahler Asten (Rothaargebirge, DE)    200k (Nordpfälzer Bergland, DE)

   
   Limburger Dom (29 July 2024, Hessen, DE)



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