I am a PhD candidate at the Mathematical Institute of Leiden University. My supervisor is Ronald van Luijk. I study rational points on varieties.

**Contact**

Snellius building, office 242

Niels Bohrweg 1, 2333 CA, Leiden

+31 (0)71 527 7142

h.d.visse@math.leidenuniv.nl

The look of this webpage was stolen from my office mate Wouter Zomervrucht.

- Mathematical Modelling (Leiden University College), spring 2018
- Mathematical Reasoning (Leiden University College), spring 2017

- Commutative Algebra, autumn 2015
- LPC student seminar, autumn 2014 - spring 2015
- Topology, spring 2014
- Linear Algebra 2 (physics), autumn 2013
- LPC student seminar, autumn 2011 - spring 2013

- Ingela Mennema, bachelor's thesis titled Lattices, spring 2016, co-supervision with Ronald van Luijk

- The density of fibres with a rational point for a fibration over hypersurfaces of low degree, joint with Efthymios Sofos.
- Calculating the Tate local pairing for any odd prime number, arXiv pre-print.
- Effective bounds for Brauer groups of Kummer surfaces over number fields, joint with Victoria Cantoral-Farfán, Yunqing Tang, and Sho Tanimoto, published in JLMS.
- Local computations on the Cassels-Tate pairing on an elliptic curve, Master's thesis, supervised by David Holmes and Rachel Newton, with official supervision by Ronald van Luijk.
- Catalysis of CO oxidation using the kinetic Monte Carlo method, Bachelor's thesis, supervised by Evgeny Verbitskiy and Joost Frenken.
- Several articles for the Leiden University Faculty of Science magazine Eureka! on assorted topics in the history of science and mathematics [issue number in parentheses]: Liquefaction of Helium [35]; Évariste Galois [37]; Alan Turing [38]; Fermat's Last Theorem [40]; Paul Dirac [45] and also several interviews with members of staff and guests, most notably Nobel laureate Klaus von Klitzing [41] and David Griffiths [44] and further [38,39,40]. Lastly, an introductory article on the topic of my Master's thesis [44].
- Het Poincarévermoeden in dimensie 2, material for the LPC course based on my own article on the subject several years ago, now with much nicer pictures.

- A heuristic for a Manin-type conjecture for K3 surfaces, Number theory lunch seminar, MPIM Bonn, February 19th, 2018
- Counting fibres with rational points, DIAMANT symposium, Breukelen, November 30th, 2017
- Towards a Manin conjecture for K3 surfaces, Journées Arithmétiques 2017, Caen, July 6th, 2017
- Explicit bounds on Brauer groups for Kummer surfaces, Nederlands Mathematisch Congress, Utrecht, April 12th, 2017
- A heuristic for a Manin-type conjecture for K3 surfaces, Forschungsseminar Arithmetische Geometrie, Berlin, November 8th, 2016
- Explicit bounds for transcendental Brauer groups of Kummer surfaces over number fields, Intercity Number Theory seminar, Leiden, October 7th, 2016
- Counting rational points of bounded height on some K3 surfaces, 2016 Student Conference of the IRTG 1800, Leiden, September 3rd, 2016
- An application of Wirsing's theorem to diagonal quartic surfaces, Kloosterman seminar, Leiden, June 30th, 2016
- Bounds on Brauer groups of Kummer surfaces DIAMANT symposium, Lunteren, November 26th, 2015
- Counting rational points on certain varieties, PhD colloquium, (notes) Leiden, October 14th, 2014
- Master's thesis defense, Leiden, March 4th, 2014

- The component group of the Néron model of a Jacobian, Seminar on Néron models (notes), Leiden, November 2nd, 2017
- Further obstructions to local-global principles, Obstructions to local-global principles (notes), Leiden, April 5th, 2017
- Brauer groups of fields, Obstructions to local-global principles (notes), Leiden, February 22nd, 2017
- The Néron–Ogg–Shafarevich criterion, Good Reduction of Abelian Varieties (notes), Amsterdam, February 17nd, 2017
- The ternary Goldbach problem, Kloosterman seminar (notes), Leiden, February 7th, 2017
- Infinitesimal sheaves and crystals, Arithmetic and Algebraic Geometry Seminar (notes), Amsterdam, November 2nd, 2016
- The period map and moduli of marked K3 surfaces, Intercity Geometry seminar (notes), Leiden, April 1st, 2016
- The Cassels–Tate pairing, seminar on rational points on elliptic curves (notes), Leiden, March 31st, 2016
- Hyperbolic Geometry of Knots, Seminar on knot theory (knotes), Leiden, February 1st, 2016
- Kontsevich' formula for rational plane curves, Seminar on moduli stacks (notes), Leiden, November 4th, 2015
- Introduction to stable maps, Seminar on moduli stacks (notes), Leiden, October 30th, 2015
- The Galois representation associated to modular forms pt. 2, Local Galois representations seminar, (notes) Leiden, May 26th, 2015
- Elliptic surfaces, K3 surfaces seminar (notes), Leiden, March 25th, 2015
- An example by Baragar in rank 4, K3 surfaces seminar (notes), Leiden, January 29th, 2015
- Hodge isometries of \(T(X)\) in odd rank and an example in rank 3, K3 surfaces seminar (notes), Leiden, January 22nd, 2015
- Finiteness results on automorphism groups of K3 surfaces, K3 surfaces seminar (notes), Leiden, December 3rd, 2014
- Further results on ample and nef cones, K3 surfaces seminar (notes), Leiden, October 28th, 2014
- Examples of K3 surfaces and introduction to Hodge decomposition, K3 surfaces seminar (notes), Leiden, September 24th, 2014
- The algebra of Hecke operators, Modular forms seminar, Leiden, May 23rd, 2013
- Finite flat group schemes, Topic in algebraic geometry seminar, Leiden, April 22nd, 2013
- Separated and proper morphisms, Topics in algebraic geometry seminar, Leiden, March 4th, 2013

- Punten tellen in de meetkunde, lunchlezing De Leidsche Flesch, Leiden, January 21st, 2015 and December 2nd, 2015
- De keukentafelmethode, ICAB meeting on mathematics education, Eindhoven, January 27th, 2012

- Algebra, Geometry and Number Theory seminar, Leiden
- Intercity Number Theory seminar, The Netherlands
- General colloquim, Leiden
- PhD colloquium, Leiden

- Rational Points on Schiermonnikoog, Schiermonnikoog, July 2nd-6th, 2018

- Journées Arithmétiques, Caen, July 3-7th, 2017
- Rational Points and Algebraic Geometry, Luminy, September 26-30th, 2016
- Explicit Methods in Number Theory, Warwick, April 4-8th,2016
- Analytic Number Theory and Diophantine Geometry, Hanover, September 7-11th, 2015
- Géométrie Algébrique en Liberté (GAeL) 2015, Leuven, June 1-5th, 2015
- Physikshows und Freihandexperimente, Bad Honnef, October 18-22nd, 2013
- ShowPhysics 2010, Bad Honnef, April 27-30th, 2010

- DIAMANT symposium, Veldhoven, April 3-4th, 2018
- DIAMANT symposium, Breukelen, November 30th-December 1st, 2017
- DIAMANT symposium, Breukelen, June 1-2nd, 2017
- Nederlands Mathematisch Congres 2017, Utrecht, April 11-12th, 2017
- DIAMANT symposium, Soest, November 24-25th, 2016
- 2016 Student Conference of the IRTG 1800, Leiden, September 3rd, 2016
- DIAMANT symposium, Veenendaal, May 26-27th, 2016
- DIAMANT symposium, Lunteren, November 26-27th, 2015
- Algebraic Geometry Seminar: B-NL meets NoGAGS, Nijmegen, June 11-12th, 2015
- Nederlands Mathematisch Congres 2015, Leiden, April 14-15th, 2015
- DIAMANT symposium, Soest, November 27-28th, 2014
- DIAMANT symposium, Arnhem, June 5-6th, 2014

- Topics in arithmetic and algebraic geometry, Mainz, October 9-13th, 2017
- Current trends in algebraic and arithmetic geometry, Vlieland, August 29th-September 2nd, 2016
- Shimura Varieties, Leiden, June 20-22nd, 2016 (co-organizer)
- LMS-CMI Summer school on Diophantine Equations, Hay-on-Wye, September 15-19th, 2015
- Recent advances in algebraic and arithmetic geometry, Siena, August 24-28th, 2015
- Arizona Winter School, Tucson, March 14-18th, 2015
- Recent Developments in Algebraic and Arithmetic Geometry, Budapest, August 25-29th, 2014

- Seminar on Néron models, Leiden, Autumn 2017
- Seminar on obstructions to local-global principles, Leiden, spring 2017 (co-organizer)
- Seminar on good reduction of abelian varieties, Amsterdam, autumn 2016 and winter 2017
- Seminar on crystalline cohomology, Amsterdam, autumn 2016
- Intercity Geometry seminar, The Netherlands, spring 2016
- Seminar on rational points on elliptic curves, spring 2016
- Seminar on knot theory, Leiden, spring 2016
- Seminar on moduli stacks, Leiden, autumn 2015 (co-organizer)
- Seminar on Local Galois representations, Leiden, spring 2015
- Seminar on K3 surfaces and their automorphisms, Leiden, autumn 2014 and spring 2015 (co-organizer)
- Seminar on étale cohomology, Leiden, autumn 2014
- Seminar on modular forms seminar, Leiden, spring 2013
- Seminar on topics in algebraic geometry, Leiden, spring 2013
- Commutative algebra seminar, Leiden, spring 2012

- Kloosterman seminar, Leiden

These are the people I share my office with.

And I have previously shared an office with the following people, for varying lengths of time.

- Abtien Javanpeykar
- Carlo Pagano
- Chloe Martindale
- Michiel Kosters
- Stefan van der Lugt
- Weidong Zhuang