This page is under construction. First created on June 21 2007
Don't forget to visit also my papers page.
Some talks I've given:
- Recent progress on th diameter of polyhedra and simplicial complexes
June 27, 2013,
This is no longer about the counter-examples to the Hirsch conjecture, but about the more general question
underlying it. It is in fact a "survey talk" reviewing several recent results by different people. Apart of FPSAC, the same talk was delivered one week earlier in SoCG 2013, in Rio de Janeiro.
- A counter-example to the Hirsch Conjecture
September 22, 2011,
DMV Jahrestagung 2011 Köln
I have spoken about my counter-example to the Hirsch conjecture many
times. This is the version delivered as invited speaker in the German
DMV Annual Meeting of 2011. This version is addressed at a general
mathematical audience. In my Hirsch page you can find versions for even more general audiences, or for more specific ones (discrete geometers). There is also a "director's cut" version delivered as a four hour minicourse in Davis, Seville, Döllnsee (Berlin) and Ellwangen.
- 50 years of the Hirsch Conjecture
17 June 2009, Renyi Institute,
and Combinatorial Geometry
This was a talk on
things related to the Hirsch Conjecture from the time when I was
working in my survey with Eddie Kim, and just before I found
counter-examples to the bounded Hirsch Conjecture (see above).
Essentially the same talk was given at
an AMS Sectional
meeting in San Francisco
and at the 2009
Congress of the Royal Spanish
Math Society in Oviedo.
Sometimes the talk had as subtitle "with focus on partial
counter-examples". In fact, the only novelyty in the talk (and in the
survey) is a new look at the Klee-Walkup unbounded non-Hirsch
polyhedron and the Mani-Walkup non-Hirsch sphere.
- The cinderella of math.
Date: 8 june 2007.
Place: Fundación Ramón Areces, Madrid
In the International Symposium "The Frontiers of Mathematics".
This talk elaborates on the
following paragraph, by A. Björner and R. P. Stanley:
development of combinatorics is somewhat like a cinderella story. It
used to be looked down on by "mainstream" mathematicians as being
somehow less respectable than other areas, in spite of many services
rendered to both pure and applied mathematics. Then along came the
prince of computer science with its many mathematical problems and
needs. And it was combinatorics that best fitted the glass slipper
You can get the PDF file (8.6 Mb) of all slides, or
the slides synchronized with the actual audio of the talk, in mov (34 Mb) or mp4 (64 Mb)
- Triangulations of polytopes
Date: 28 August 2006.
Place: Palacio de Congresos, Madrid.
In the International Congress of Mathematicians.
A talk introducing some aspects of triangulations of polytopes and their relation to several areas of mathematics (computational geometry, topological combinatorics, algebraic geometry). Intended for general mathematical audiences.
You can get the PDF file (~800K) of all slides.
See also the paper
- Introducción a la Teoría de la Rigidez (Introduction to rigidity theory)
Date: 25 July 2006
Place: El Escorial, Madrid.
In the II Escuela de Educación Matemática Miguel de Guzmán".
A talk in Spanish introducing rigidity theory. It owes a lot to the very nice booklet "Counting of Frameworks" by Jack Graver (Dolciani Mathematical Expositions, n. 25, Mathematical Association of America, 2001).
You can get the PDF file (~1700K) of all slides.