Home page of Bart Litjens

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I am a PhD student at the University of Amsterdam under supervision of Alexander Schrijver. I am interested in applying methods from algebra, geometry and representation theory to problems in discrete mathematics. My main interests center around bounds in coding theory using semidefinite programs and polynomial invariants for (embedded) graphs. I am funded by an ERC Advanced Grant (AFMIDMOA).

Contact information

b dot m dot litjens at uva dot nl
+31 (0)20 525 8206

Room F3.28
Korteweg-de Vries Institute for Mathematics
University of Amsterdam
Science Park 107
Postbus 94248
1090 GE Amsterdam

Supervising

Bachelor's thesis Semester Student
Coding theory Spring 2017 Eline Filius
Second year project Semester Students
Roots of the independence polynomial Spring 2017 Joris Blok, Fjodor van Hoof
Group cohomology and group extensions Spring 2016 Dimitri Geelhoed, Manuel Van
Sylow theorems and classification of finite groups Spring 2016 Emma van der Grijp, Yvette van Nek
Rational points on elliptic curves Spring 2015 Wouter de Koning, Ugur Taytas

Talks

Conference/Seminar Topic Date Place
Discrete Math. Seminar Coloring signed graphs Notes 28-2-2018 UvA/CWI, Amsterdam
Lunteren Conference 2018 Bounds in coding theory and the crossing number problem Slides 17-1-2018 Lunteren, the Netherlands
Discrete Math. Seminar Coloring triangle-free graphs with large minimum degree Notes 29-11-2017 UvA/CWI, Amsterdam
Eurocomb 2017 A Tutte polynomial for maps Slides 1-9-2017 Vienna, Austria
Discrete Math. Seminar A theorem on perfect codes Notes 31-5-2017 UvA/CWI, Amsterdam
Workshop Analytic Combinatorics Counting flows in embedded graphs Slides 31-3-2017 Zamecek, Czech Republic
Discrete Math. Seminar The Frobenius-Schur indicator 22-3-2017 UvA/CWI, Amsterdam
Discrete Math. Seminar Kneser's Conjecture and the Borsuk-Ulam Theorem 29-11-2016 UvA/CWI, Amsterdam
Master Seminar in Algebra and Geometry Counting solutions of equations in finite groups Notes 28-11-2016 UvA, Amsterdam
Workshop on Algebraic Graph Theory Semidefinite bounds for mixed binary/ternary codes Slides 6-10-2016 Pilsen, Czech Republic
Discrete Math. Seminar Partition functions from representations and flow-coloring duality for embedded graphs 20-9-2016 UvA/CWI, Amsterdam
5th SDP Day New upper bounds for mixed and nonbinary codes based on triples and quadruples Slides 30-6-2016 CWI, Amsterdam
JCCA 2016 New upper bounds for nonbinary codes based on quadruples Slides 24-5-2016 Kyoto University, Japan
Discrete Math. Seminar Kirchoff polynomials and a conjecture of Kontsevich 15-4-2016 UvA/CWI, Amsterdam
Discrete Math. Seminar Counting solutions of equations in finite groups 8-1-2016 UvA/CWI, Amsterdam
Discrete Math. Seminar Code upper bounds and semidefinite programming 30-10-2015 UvA/CWI, Amsterdam
Discrete Math. Seminar Algebraic matroids 26-6-2015 UvA/CWI, Amsterdam
Discrete Math. Seminar Repr. theory of the symmetric group, after Okounkov and Vershik 29-5-2015 UvA/CWI, Amsterdam
Discrete Math. Seminar Graph groups 18-4-2015 UvA/CWI, Amsterdam
Discrete Math. Seminar Knot theory and Vassiliev invariants 21-11-2014 UvA/CWI, Amsterdam
Discrete Math. Seminar Schur-Weyl duality and the FFT for GL(n,C) 19-9-2014 UvA/CWI, Amsterdam
Master thesis presentation Good reduction of abelian varieties 22-4-2014 UvA/VU, Amsterdam
Syzygien in der algebraischen Geometrie Castelnuovo-Mumford regularität 18-7-2013 FU, Berlin
p-adischen Galois Darstellungen Galoiskohomologie 2-6-2013 HU, Berlin

Teaching

Courses Semester
Representation theory Autumn 2017
Graph theory Spring 2017
Linear algebra Autumn 2016
Algebra 1 (group theory) Spring 2016
Algebra 2 (ring and field theory) Autumn 2015
Matching Wiskunde (introduction to analysis) Summer 2015
Algebra 1 (group theory) Spring 2015
Algebra 2 (ring and field theory) Autumn 2014
Algebra 2 (ring and field theory) Autumn 2013

Writing

In preparation
-A.J. Goodall, B.M. Litjens, G. Regts and L. Vena, A new Tutte polynomial for signed graphs

Preprints
-A.J. Goodall, B.M. Litjens, G. Regts and L. Vena, A Tutte polynomial for maps II: the non-orientable case. (2018; preprint arXiv:1804.01496
-B.M. Litjens, S.C. Polak, B.L. Sevenster and L. Vena, On the chromatic number of a subgraph of the Kneser graph. (2018; preprint arXiv:1803.04342)
-B.M. Litjens, S.C. Polak and V. Sivaraman, Sum-perfect graphs. (2017; preprint arXiv:1710.07546)
-B.M. Litjens, On dihedral flows in embedded graphs. (2017; preprint arXiv:1709.06469)

Published
-B.M. Litjens and B.L. Sevenster, Partition functions and a generalized coloring-flow duality for embedded graphs. Journal of Graph Theory, 88 (2) (2018), 271-283. Journal, arXiv:1701.00420
-B.M. Litjens, Semidefinite bounds for mixed binary/ternary codes. Discrete Mathematics, 341 (6) (2018), 1740-1748. Journal, arXiv:1606.06930
-B.M. Litjens, S.C. Polak and A. Schrijver, Semidefinite bounds for nonbinary codes based on quadruples. Designs, Codes and Cryptography, 84 (1) (2017), 87-100. Journal, arXiv:1602.02531

Refereed conference proceedings
-A.J. Goodall, B.M. Litjens, G. Regts and L. Vena, A Tutte polynomial for non-orientable maps. Electronic Notes in Discrete Mathematics, 61 (2017), 513-510 Journal

Thesis
My master thesis, titled `Good reduction of abelian varieties', was written under the supervision of Gerard van der Geer.

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