Material from lectures 

The picture is a page from "Het bloedig Tooneel, of Martelaars Spiegel" from 1685 (book 2, page 425), a book describing various kinds of tortures - as in this example: to have to have a dispute with Mr Broer Cornelis (sic). As a modern equivalent, I offer some of my lectures.

Encounters with tori
2012 Charles DePrima Memorial Lecture, Caltech
pdf sheets

Reconstructing number fields with noncommutative geometry
Workshop C*-algebras and nunber theory, Munster, 2011
pdf sheets

Het Erlangenprogramma van Klein
Nationale Wiskunde Dagen (2011)
(5MB) Powerpoint pptx or pdf sheets

Luisteren naar vormen
Ouderdag Studentenvereniging A-eskwadraat Utrecht (2008)
zipped (11MB!) Powerpoint package (with sound and video)

De Wonderbare Wiskundige Keuken
Ouderdag Studentenvereniging A-eskwadraat Utrecht (2007)
pdf sheets

Hard Number Theoretical Problems and Elliptic Curves
Conference on "Hilbert's tenth Problem'', Clay Mathematics Institute and CUNY Collaborative Number Theory Seminar (2007)
pdf sheets

Voor welke m en n is 1+...+m = 1²+...+n²?
Voorlichtingsdag Wiskunde (Utrecht, 2003), Wiskunde-olympiade 2e ronde (2010), ...
pdf sheets

Theorem G of Taylor's article "Remarks on a conjecture of Fontaine and Mazur"
Intercity Number Theory Seminar Lecture (Utrecht 2005)
pdf notes compiled by Peter Bruin 

Euler, Balonnen en de Rest
Vierkant voor Wiskunde Zomerkamp (Lunteren, 2005)
pdf sheets

Drinfeld modular curves in algebraic Geometry
XVIeme Rencontres Arithmétiques (Caen, 2005)
pdf sheets

Improving Julia Robinson (conjecturally)
Workshop "Hilbert's tenth Problem'', AIM (Palo Alto, 2005)
pdf sheets

Diophantische vergelijkingen vanuit de verte bekeken
Nationale Wiskunde Dagen (Noordwijkerhout, 2004)
pdf sheets en pdf artikel met werkbladen

What is more difficult, solving equations in integers or in rational numbers?
Colloquium Lecture, and Intercity Number Theory Seminar Lecture (Utrecht 2005)
pdf sheets en pdf artikel 
The original lecture has sound under the button "Radio Sound" on p. 4; this should work if you download the pdf-sheets via the above link, copy the file .../htplezing/hilberte.wav to the same directory, and view the pdf using acrobat reader, version > 4.

Geschiedenis van het groepentheorie-concept (naar Wussing)
College Groepentheorie (Utrecht, 2003)
pdf sheets