Faculty

Faculty > Professors > IHRINGER Ferdinand

IHRINGER Ferdinand

Assistant Professor

ihringer@sustech.edu.cn

Brief Biography
Research
Teaching
Published Works

Degrees

2015: Dr. rer. nat. (Phd) at the JLU Gießen under the supervision of Klaus Metsch.
2012: Master of Science in mathematics at the JLU Gießen.
2009: Bachelor of Science in mathematics at the JLU Gießen.

Positions

11/2023-01/2030: Tenure-track Assistant Professor at the Southern University of Science and Technology (SUSTech), Shenzhen, China.
10/2023: Associated postdoctoral researcher at Gent University. Supervisor: Leo Storme.
10/2020-09/2023: Senior Postoctoral Researcher of the Flemish Research Foundation (FWO) at Gent University. Supervisor: Leo Storme.
10/2017-09/2020: Postoctoral Researcher of the Flemish Research Foundation (FWO) at Gent University. Supervisor: Leo Storme.
09/2018-10/2018: Research Fellow at the Graduate School of Information Sciences, Tohoku University, Sendai, Japan.
07/2017-01/2018: Postdoctoral Researcher at the Hebrew University of Jerusalem. Supervisor: Gil Kalai.
07/2016-06/2017: Postdoctoral Fellow of the Pacific Institute of the Mathematical Sciences at the University of Regina. Supervisor: Karen Meagher.
05/2012-06/2016: Scientific Assistant of Prof. Dr. Albrecht Beutelspacher/Doctoral Researcher under Prof. Dr. Klaus Metsch in the Mathematical Institute at Giessen University.
04/2008-04/2012: Teaching Assistant in the Mathematical Institute at Giessen University.

Research Visits/International Collaborations

05/2023: 3 days with Anurag Bishnoi at the TU Delft.
05-06/2022: 2 weeks with Karen Meagher at the University of Regina.
05/2022: 4 days with Sebastian Cioaba and Felix Lazebnik at the University of Delaware.
11-12/2021: 6 weeks with Jacques Verstraete, University of California San Diego.
12/2019: 5 weeks with John Bamberg, Anurag Bishnoi, Gordon Royle and others at the University of Western Australia.
05/2019: 4 days with Sebastian Cioaba, Felix Lazebnik and Qing Xiang at the University of Delaware.
03/2019: 2 weeks with Yuval Filmus at the Technion.
02/2019: 4 days with Anurag Bishnoi and Tibor Szabo at the FU Berlin.
01/2019: 5 days with Lilya Budaghyan at the University of Bergen.
09/2018-10/2018: 2 months with Akihiro Munemasa and Hajime Tanaka at Tohoku University.
05/2017: 5 days with Peter Dukes at the University of Victoria, BC.
05/2017: 9 days with Eric Moorhouse and Jason Williford at the University of Wyoming.
04/2017: 5 days with Anton Betten and Tim Penttila at Colorado State University.
04/2017: 4 days with Sebastian Cioaba, Felix Lazebnik and Qing Xiang at the University of Delaware.
08/2016: 2 weeks with Chris Godsil and Krystal Guo at the University of Waterloo.
03-04/2016: 25 days with Karen Meagher at the University of Regina.
02-03/2016: 5 days with Sebastian Cioaba, Felix Lazebnik and Qing Xiang at the University of Delaware.
06/2015: 10 days with Karen Meagher at University of Regina.
03/2014: 3 weeks with Jan De Beule at the mathematics department at the University of Ghent.
02-04/2013: 6 weeks with John Bamberg at the School of Mathematics and Statistics at the University of Western Australia.

Grants and Fellowship

I received the following grants.

FWO Senior Postdoctoral Researcher, Flemish Research Foundation, 2020–2023.
FWO Postdoctoral Researcher, Flemish Research Foundation, success rate 2017: 0.2739, 2017–2020.
FWO Long Term Research Stay Abroad, Flemish Research Foundation, 2021, for the USA.
FWO Long Term Research Stay Abroad, Flemish Research Foundation, 2019, for Australia.
FWO Long Term Research Stay Abroad, Flemish Research Foundation, 2018, for Japan.
PIMS Postdoctoral Fellowship, Pacific Institute of the Mathematical Sciences, 2016–2017.
Research Trust Fund of the University of Regina, 2017.

Furthermore, I successfully applied for the following grants:

Conference Fund of the Pacific Institute for the Mathematical Sciences, 2016.
Conference Fund of the University of Regina, 2016.

Service

Organized Conferences

The Prairie Discrete Math Workshop 2017, Lumsden Saskatchewan, 2–5 June, 2017.

Publications

My work (mainly) covers extremal combinatorics, finite geometry, spectral graph theory, and coding theory.

My Favorite Publications/Preprints

Here my some of my favorite papers, subjectively ranked. A complete list of all my publications can be found below.

The classification of Boolean degree 1 functions in high-dimensional finite vector spaces.
Submitted. Preprint.
With Hajime Tanaka: The Independence Number of the Orthogonality Graph in Dimension 2^k.
Combinatorica, 2019. Preprint.
With Yuval Filmus: Boolean degree 1 functions on some classical association schemes.
Journal of Combinatorial Theory A, 2019. Preprint.
With Andries E. Brouwer and William M. Kantor: Strongly regular graphs satisfying the 4-vertex condition.
Combinatorica, 2023. Preprint.
With Peter Sin and Qing Xiang: New Bounds for Partial Spreads of H(2d-1, q^2) and Partial Ovoids of the Ree-Tits Octagon.
Journal of Combinatorial Theory A, 2018. Preprint.
With Anurag Bishnoi and Valentina Pepe: A construction for clique-free pseudorandom graphs.
Combinatorica, 2020. Preprint.

Publications/Preprints Chronologically

Please note that sometimes there are differences between the preprint and the journal version of a paper.

The classification of Boolean degree 1 functions in high-dimensional finite vector spaces. Preprint.
With Morgan Rodgers: Regular Sets of Lines in Rank 3 Polar Spaces. Preprint.
With Paulien Jansen, Linde Lambrecht, Yannick Neyt, Daan Rijpert, Hendrik Van Maldeghem, Magali Victoor:
Local recognition of the point graphs of some Lie incidence geometries.
Submitted. Preprint.
The strongly regular twisted D_{5,5}(q) graph.
Discrete Applied Mathematics, Minor Revisions. Preprint.
On MSR Subspace Families of Lines.
Advances in Mathematics of Communications, 2023. Preprint.
With Yuval Filmus, Edward Hirsch, Sascha Kurz, Artur Riazanov, Alexander Smal, Marc Vinyals: Irreducible subcube partitions.
Electronic Journal of Combinatorics, 2023. Preprint.
With John Bamberg, Yuval Filmus, Sascha Kurz: Affine vector space partitions.
Designs, Codes and Cryptography, 2023. Preprint.
With Stephen P. Glasby and Sam Mattheus: The proportion of non-degenerate complementary subspaces in classical spaces.
Designs, Codes and Cryptography, 2023. Preprint.
Non-Geometric Cospectral Mates of Line Graphs with a Linear Representation.
Journal of Geometry, 2023. Preprint.
With Andries E. Brouwer and William M. Kantor: Strongly regular graphs satisfying the 4-vertex condition.
Combinatorica, 2023. Preprint.
Approximately Strongly Regular Graphs.
Discrete Mathematics, 2023. Preprint.
With Jan De Beule, Jozefien D'haeseleer, Jonathan Mannaert: Degree 2 Boolean Functions on Grassmann Graphs.
Electronic Journal of Combinatorics, 2023. Preprint.
With Sebastian M. Cioabă, Himanshu Gupta, Hirotake Kurihara: The least Euclidean distortion constant of a distance-regular graph.
Discrete Applied Mathematics, 2022. Preprint.
Switching for Small Strongly Regular Graphs.
Australasian Journal of Combinatorics, 2022. Preprint.
With Francesco Pavese and Valentino Smaldore: Graphs cospectral with NU(n+1, q^2), n ≠ 3.
Discrete Mathematics, 2021. Preprint.
With Jozefien D'haeseleer, Jonathan Mannaert, Leo Storme: Cameron-Liebler k-sets in AG(n,q).
Electronic Journal of Combinatorics, 2021. Preprint.
Remarks on the Erdős Matching Conjecture for Vector Spaces.
European Journal of Combinatorics, 2021. Preprint.
With Lilya Budaghyan, Claude Carlet, Diana Davidova, Tor Helleseth, Tim Penttila:
Relation between o-equivalence and EA-equivalence for Niho bent functions.
Finite Fields and Their Applications, 2021. Preprint.
With Deepak Rajendraprasad and Thilo Weinert: New bounds on the Ramsey number r(I_m, L_n).
Discrete Mathematics, 2021. Preprint.
With Peter J. Dukes and Nathan Lindzey: On the Algebraic Combinatorics of Injections and its Applications to Injection Codes.
IEEE Transactions on Information Theory, 2020. Preprint.
With Peter J. Dukes and Nathan Lindzey: On the Algebraic Combinatorics of Injections (extended abstract).
Proceedings of the 32nd Conference on Formal Power Series and Algebraic Combinatorics, 2020.
With Daniel Heinlein: New and Updated Semidefinite Programming Bounds for Subspace Codes.
Advances in Mathematics of Communications, 2020. Preprint.
With Anurag Bishnoi and Valentina Pepe: A construction for clique-free pseudorandom graphs.
Combinatorica, 2020. Preprint.
With Hajime Tanaka: The Independence Number of the Orthogonality Graph in Dimension 2^k.
Combinatorica, 2019. Preprint.
With Andrey Kupavskii: Regular Intersecting Families.
Discrete Applied Mathematics, 2019. Preprint.
The Chromatic Number of the q-Kneser Graph for large q.
Electronic Journal of Combinatorics, 2019. Preprint.
With Yuval Filmus: Boolean constant degree functions on the slice are juntas.
Discrete Mathematics, 2019. Preprint.
With Yuval Filmus: Boolean degree 1 functions on some classical association schemes.
Journal of Combinatorial Theory A, 2019. Preprint.
With Akihiro Munemasa: New Strongly Regular Graphs from Finite Geometries via Switching.
Linear Algebra and Its Applications, 2019. Preprint.
With Mohammad Adm, Ryan Bergen, Sam Jaques, Karen Meagher, Alison Purdy, Boting Yang:
Ovoids of Generalized Quadrangles of Order (q,q^2−q) and Delsarte Cocliques in Related Strongly Regular Graphs.
Journal of Combinatorial Designs, 2018. Preprint.
With Peter Sin and Qing Xiang: New Bounds for Partial Spreads of H(2d-1, q^2) and Partial Ovoids of the Ree-Tits Octagon.
Journal of Combinatorial Theory A, 2018. Preprint.
With Klaus Metsch and Bernhard Mühlherr: An EKR theorem for finite buildings of type Dl.
Journal of Algebraic Combinatorics, 2018.
With Karen Meagher: Manickam-Miklós-Singhi Conjectures on Partial Geometries.
Designs, Codes and Cryptography, 2018. Preprint.
With Klaus Metsch: Large {0, 1,...,t}-Cliques in Dual Polar Graphs.
Journal of Combinatorial Theory A, 2018. Preprint.
With Andries E. Brouwer, Sebastian M. Cioabă, and Matt McGinnis:
The smallest eigenvalues of Hamming graphs, Johnson graphs and other distance-regular graphs with classical parameters.
Journal of Combinatorial Theory B, 2018. Preprint.
With Ryan Bergen, Shaun Fallat, Adam Gorr, Karen Meagher, Alison Purdy, Boting Yang, Guanglong Yu: Infection in Hypergraphs.
Discrete Applied Mathematics, 2018. Preprint.
With Anurag Bishnoi: The non-existence of distance-2 ovoids in H(4)^D.
Contributions to Discrete Mathematics, 2017. Preprint.
With John Bamberg and Jan De Beule: New non-existence proofs for ovoids of Hermitian polar spaces and hyperbolic quadrics.
Annals of Combinatorics, 2017. Preprint.
A Switching for Strongly Regular Collinearity Graphs From Polar Spaces.
Journal of Algebraic Combinatorics, 2017. Preprint.
A Note on the Manickam-Miklós-Singhi Conjecture for Vector Spaces.
European Journal of Combinatorics, 2016. Preprint.
Cross-intersecting Erdős-Ko-Rado Sets in Dual Polar Graphs.
Electronic Journal of Combinatorics, 2015.
A new upper bound for constant distance codes of generators on hermitian polar spaces of type H(2d − 1, q^2).
Journal of Geometry, 2014. Preprint.
With Klaus Metsch: On the Maximum Size of Erdős-Ko-Rado Sets in H(2d+1, q^2).
Designs, Codes and Cryptography, 2014. Preprint.
A Characterisation of the Natural Embedding of the Split Cayley Hexagon in PG(6,q) by Intersection Numbers in Finite Projective Spaces of Arbitrary Dimension.
Discrete Mathematics, 2014. Preprint.

Unpublished/Unrefereed Reports

With Gary Greaves, Franklin Kenter, Brendan Rooney: Answer to IMAGE Problem 67-1, Answer, 2022.
Partial m-Spreads of Hermitian Polar Spaces, Report, 2022.
With Jacques Verstraëte: Large (k; r, s; n, q)-sets in Projective Spaces.
2022. Preprint.
Two Small Improvements on Ramsey Numbers, 2020.
Report on the GM-Switching Class of Sp(6, 2), 2020. Superseded by: Switching for Small Strongly Regular Graphs.

Coauthors

Yuval Filmus (4), Karen Meagher (3), Klaus Metsch (3), John Bamberg (2), Ryan Bergen (2), Anurag Bishnoi (2), Andries E. Brouwer (2), Sebastian M. Cioabă (2), Jan De Beule (2), Jozefien D'haeseleer (2), Sascha Kurz (2), Jonathan Mannaert (2), Alison Purdy (2), Boting Yang (2), Mohammad Adm, Lilya Budaghyan, Claude Carlet, Diana Davidova, Peter J. Dukes, Shaun Fallat, Stephen P. Glasby, Adam Gorr, Himanshu Gupta, Daniel Heinlein, Tor Helleseth, Edward Hirsch, Paulien Jansen, Sam Jaques, William M. Kantor, Andrey Kupavskii, Hirotake Kurihara, Linde Lambrecht, Nathan Lindzey, Matt McGinnis, Sam Mattheus, Bernhard Mühlherr, Akihiro Munemasa, Yannick Neyt, Francesco Pavese, Tim Penttila, Valentina Pepe, Deepak Rajendraprasad, Artur Riazanov, Daan Rijpert, Morgan Rodgers, Peter Sin, Alexander Smal, Valentino Smaldore, Leo Storme, Hajime Tanaka, Hendrik Van Maldeghem, Magali Victoor, Marc Vinyals, Thilo Weinert, Qing Xiang, Guanglong Yu.

Plenary Speaker Conferences/Workshop

TBA, The 9th International Workshop on Boolean Functions and their Applications (BFA), Dubrovnik, Croatia, 2024.
Quadratic forms and clique-free graphs, CanaDAM 2023, Winnipeg, Manitoba, Canada, 2023.
The Coclique Number of Orthogonality Graphs, Three days of computational methods for extremal discrete geometry, Köln, Germany, 2022.
Low Degree Boolean Functions in Finite Geometry, Finite Geometry and Extremal Combinatorics, Newark, Delaware, USA, 2019.
Polymath 10: Inequalities Related to the Sunflower Conjecture, IntersectionFest 2016, VCU, Richmond, Virginia, 2016.

Invited Speaker Conferences/Colloquia/Online Workshop

TBA, Conference to celebrate the birthday of Paul Terwilliger, Kranjska Gora, Slovenia, 2025.
Variations of the Erdős-Ko-Rado problem, Open Problems in Algebraic Combinatorics, Waterloo, Canada, 2021.
Cospectral Strongly Regular Graphs in Geometrical Settings, Prairie Discrete Math Workshop 2017, Lumsden, Saskatchewan, Canada, 2017.
Erdős-Ko-Rado Sets in Finite Geometries, Colloquium to the memory of Thomas Ihringer. TU Darmstadt, 2015.
On the Maximum Size of M-Cliques of Generators on Hermitian Polar Spaces. Colloquium on Galois geometry. To the memory of Frédéric Vanhove. Ghent, 2014.
Erdős-Ko-Rado Mengen in endlichen Polarräumen (German), 100. Baerkolloquium, Gießen, 2013.

Seminar/Invited Session/Online Workshop Talks

Some methods for modifying strongly regular graphs, TU Darmstadt, Darmstadt, Germany, 2023.
Strongly regular graphs satisfying the 4-vertex condition, Dutch-Belgian Discrete Math Seminar, VUB, Brussels, Belgium, 2023.
Some methods for modifying strongly regular graphs, TU Delft, Delft, The Netherlands, 2023.
Switchings from Strongly Regular Graphs, Zoom Seminar, Combinatorics Seminar U. Wisconsin-Madison Mathematics, Madison, Wisconsin, USA, 2023.
Low Degree Boolean Functions in Grassmann Graphs, Seminar of TWAG Study Group (Recording), National Sun Yat-sen University, Sizihwan, Taiwan, 2022.
Strongly Regular Graphs, Seminar of TWAG Study Group (Recording), National Sun Yat-sen University, Sizihwan, Taiwan, 2022.
Caps and Probabilistic Methods, University of Regina, Regina, Saskatchewan, Canada, 2022.
Caps and Probabilistic Methods, University of Delaware, Newark, Delaware, USA, 2022.
Low Degree Sets in Finite Geometry, UC San Diego Combinatorics Seminar, La Jolla, California, USA, 2021.
The Erdős-Matching Conjecture, Low Degree Boolean Functions and Their q-Analogs, Sabanci Algebra Seminar (Zoom), Turkey, 2021.
Pseuodrandom Cliquefree Graphs, Finite Geometry, and Spectra, Zoom Seminar, Waterloo University, Algebraic Graph Theory Seminar, Waterloo, Canada, 2020.
Extremal eigenvalues of (generalized) Hamming graphs, Johnson graphs, and Grassmann graphs, Zoom Seminar, University of Western Australia, Perth, Australia, 2020.
Low Degree Boolean Functions in Finite Geometry, University of Western Australia, Perth, Australia, 2019.
A Construction for Cospectral Graphs, University of Delaware, Newark, Delaware, USA, 2019.
A Construction for Cospectral Graphs, University of Bergen, Bergen, Norway, 2019.
Rank Bounds on the Independence Number, Ben-Gurion University of the Negev, Beersheba, Israel, 2019.
Rank Bounds on the Independence Number, FU Berlin, Berlin, Germany, 2019.
Boolean Degree 1 Functions on Some Classical Domains, University of Bergen, Bergen, Norway, 2019.
Three Perspectives on Boolean Degree 1 Functions, Tohoku University, Sendai, Japan, 2018.
Subsets in Association Schemes, Tel Aviv University, Tel Aviv, Israel, 2018.
Ovoids in Generalized Quadrangles, University of Wyoming, Laramie, Wyoming, USA, 2017.
Large Erdős-Ko-Rado Sets in Polar Spaces, Colorado State University, Fort Collins, Colorado, USA, 2017.
Ovoids in Generalized Quadrangles, University of Delaware, Newark, Delaware, USA, 2017.
Intriguing Sets in Generalized Quadrangles, Hexagons, and Octagons, Kutztown University, Pennsylvania, USA, 2017.
Erdős-Ko-Rado Sets in Finite Geometries, Rutgers University, New Jersey, USA, 2017.
Erdős-Ko-Rado Sets in Finite Geometries, University of Regina, Regina, Saskatchewan, 2016.
Intriguing Sets in Generalized Quadrangles and Hexagons, University of Waterloo, Waterloo, Ontario, 2016.
The Manickam-Miklós-Singhi Conjecture for Partial Linear Spaces, BLS 2016, Logroño, 2016.
Intriguing Sets in Generalized Quadrangles and Hexagons, University of Regina, Regina, Saskatchewan, 2016.
Erdős-Ko-Rado Sets in Finite Spherical Buildings, University of Delaware, Newark, Delaware, 2016.
Erdős-Ko-Rado Sets in Finite Classical Polar Spaces, University of Western Australia, Perth, 2013.

Contributed Talks

The Twisted E66(q) graph, Summerschool Finite Geometry and Friends, Brussels, Belgium, 2023.
Affine vector space partitions, Workshop Combinatorics in Digital Communication, Eindhoven University of Technology (TU/e), Netherlands, 2023.
Conditions on Large Caps, Finite Geometries 6, Irsee, Germany, 2022.
The Density of Complementary Subspaces, ILAS 2022, Galway, Ireland, 2022.
The Density of Complementary Subspaces, Prairie Discrete Math Workshop, Online, Canada, 2022.
Strongly regular graphs satisfying the 4-vertex condition, ECM 2020, Slovenia, 2021.
Strongly regular graphs satisfying the 4-vertex condition, CanaDAM 2021, Canada, 2021.
Finite Geometry and switching in graphs, Finite geometry: a workshop in honour of Tim Penttila, Adelaide, Australia, 2019.
New SDP Bounds on Subspace Codes, Bled19: 9th International Slovenian Conference on Graph Theory, Bled, Slovenia, 2019.
The Independence Number of the Orthogonality Graph, Summerschool Finite Geometry and Friends, Brussels, Belgium, 2019.
Regular Intersecting Families, Kolkom 2018, Paderborn, Germany, 2018.
Three Perspectives on Cameron-Liebler Line Classes, Combinatorics 2018, Arco, Italy, 2018.
Strongly Regular Graphs Related to Polar Spaces, Finite Geometries, Fifth Irsee Conference, Irsee, 2017.
The Largest t-Intersecting Erdős-Ko-Rado Sets of Polar Spaces, MCGTC, Malta, 2017.
A Switching for the Collinearity Graphs of Polar Spaces, Western Sectional Meeting of the AMS, Denver, Colorado, 2016.
New Bounds on the Ramsey Numbers r(In, L3), Combinatorics 2016, Maratea, 2016.
The Manickam-Miklós-Singhi Conjecture for Vector Spaces, System of Lines: Applications of Algebraic Combinatorics, Worcester Polytechnic Institute, Worcester, MA, 2015.
Erdős-Ko-Rado Sets and Semidefinite Programming in Hermitian Polar Spaces, Workshop on Algebraic Combinatorics, Tilburg, 2015.
Erdős-Ko-Rado Sets and Semidefinite Programming in Hermitian Polar Spaces, CanaDAM, 2015.
The Manickam-Miklós-Singhi Conjecture for Vector Spaces. Finite Geometries, Fourth Irsee Conference, 2014.
Erdős-Ko-Rado Sets in Finite Classical Polar Spaces, Fq11, Magdeburg, 2013.
Erdős-Ko-Rado Sets in Hermitian Polar Spaces, Combinatorics 2012, Perugia, 2012.

Theses

PhD Thesis (English), Algebraic Combinatorics Intersecting Finite Geometry, 2015.
Master Thesis (German), Intriguing Sets in Polar Spaces, 2011.
Bachelor Thesis (German), $1 \equiv p$ Results in Finite Projective Spaces, 2009.