The Mathematical Institute Newsletter is maintained by Jan-Hendrik Evertse. The newsletter is issued the first week of each month, except for July and August. The electronic version of the newsletter can be found on http://www.math.leidenuniv.nl/~evertse/newsletter.shtml
(go to the homepage of the Mathematical Institute and click on "Newsletter").

Copy for the February 2005 newsletter, such as announcements, personal notes, visits to conferences, guests (with place of origin and date of arrival and departure), lectures of general interest, Ph.D. thesis defenses (with title of thesis), etc. should be sent by e-mail to evertse at math.leidenuniv.nl before January 27. Copy should be submitted in English plaintext, so that it can be inserted into the newsletter without time consuming typing or translating work.

Agenda and announcements

• Bas Edixhoven gets Vici-grant
   
  Each year, NWO allocates some Vici-grants to outstanding senior researchers to build up a research group. Vici-grants are financially supported by NWO, in cooperation with the VSNU and the OCW. Together with the Veni-grants and Vidi-grants for younger researchers, they make up the "NWO-vernieuwingsimpulsprogramma" (NWO-programme to stimulate innovative research).
  One of the Vici-grants for 2005 has been awarded to Bas Edixhoven for his project "Arithmetic geometry, motives: computational aspects." The research proposal can be found at http://www.math.leidenuniv.nl/~edix/FormVICIdetail_2004.pdf.

• Cooperation between general mathematics colloquia of Delft and Leiden
   
  During the next spring, there will be a cooperation between the general mathematics colloquia of Delft and Leiden. The intention is, that some people from Delft will give a lecture at the colloquium in Leiden, and that some people from Leiden will speak in Delft. Further details will follow.

• New Year's reception on Monday January 10
   
  The annual New Year's reception of the Faculty of Sciences is on January 10 in the entrance hall of the Gorlaeus laboratory. The reception starts at 4:00 pm. From 3:30-4:00 there is a possibility to vote for the "Discoverer of the year 2004." During the reception, the chairman of the university board, A.W. Kist will present the C.J. Kok prizes to the discoverers of 2004.

• Stieltjes afternoon on Thursday January 13 in Tilburg
   
  On occasion of its accession to the Stieltjes Institute, the Universiteit van Tilburg organizes a Stieltjes afternoon on January 13. On this afternoon there will be lectures by Hans Schumacher, Peter Spreij, Dolf Talman and Bas Werker. Further, the rector of the Universiteit van Tilburg will present the Stieltjes prize for the best Ph.D. thesis in 2003 written at one of the universities participating in the Stieltjes institute.
  For further information, see http://www.tilburguniversity.nl/faculties/feb/econometrics/stieltjesafternoon.

• Special day on Mathematics of Cryptology on Friday January 21 at the Lorentz Center
   
  This is a joint meeting of the RISC Seminar of the Cryptology and Information Security group at CWI and the Intercity Number Theory Seminar.
  Organizers: Ronald Cramer and Bart de Smit. Details are on the websites http://www.cwi.nl/projects/crypto/risc.html, http://www.math.leidenuniv.nl/~desmit/ic

• Number theory lectures on Tuesday January 25 and Wednesday January 26
   
  On January 25 and 26 there is a number theory seminar, with lectures by some guests from Hungary as well as some people from Leiden. Part of the program will be a lecture by Szabolcs Tengely on January 25 at 4:00 pm in which he discusses the contents of his Ph.D. thesis. All lectures are in room 174 of the Snellius. The detailed program is as follows:

  Tuesday January 25:
  2:00		Ákos Pintér (Debrecen): Applications of the binomial Thue-like equations
  3:00		Attila Bérczes (Debrecen): On the number of equivalence classes of binary forms with given degree and given discriminant
  4:00		Szabolcs Tengely: On effective methods for Diophantine equations
  Wednesday January 26:
  2:00		Lajos Hajdu (Debrecen): On the problems of Turán and Szegedy concerning irreducible polynomials
  3:00		Joost Batenburg: On the reconstruction of crystals through discrete tomography
  4:00		Sierk Rosema: On the Tribonacci substitution

• Ph.D. thesis defense by Szabolcs Tengely on Thursday January 27
   
  Szabolcs Tengely will defend his Ph.D. thesis on January 27 at 2:15 pm in the Academiegebouw, Rapenburg 73.
  Title: Effective methods for Diophantine equations
  Supervisor: Prof. Robert Tijdeman

• New full professors

  - Prof. Ronald Cramer in cryptology per June 1, 2004 (one day per week in Leiden, four days per week at CWI)

  - Prof. Jan Hogendijk in the history of mathematics per September 1, 2004 (one day per week)

  "Jan Hogendijk studied mathematics at the University of Utrecht, with second subject Arabic. He received his Ph. D. in Utrecht in 1983. His dissertation was a critical edition with English translation and commentary, of an un published tenth-century Arabic text on conic sections. He worked for two years at the History of Mathematics Department at Brown University, Providence R.I., and one year at the History of Science Department of the J.W. Goethe University in Frankfurt am Main (Germany). Since 1986 until the present, he has been a member of the Department of Mathematics of the University of Utrecht. He has published extensively on the history of the mathematical sciences between antiquity and the 17th century, with emphasis on Islamic civilization. In September 2004 he became part-time professor in History of Mathematics at the University of Leiden, and adjunct professor in the Department of Mathematical Sciences of King Fahd University of Petroleum and Minerals in Dhahran (Saudi Arabia). See the website http://www.math.uu.nl/people/hogend.

  - Prof. Frank den Hollander in probability theory per September 1, 2004 (one day per week until October 1, 2005 after that full time)

  "In the past, my research interests have been in the area of probability theory, mathematical statistical physics and ergodic theory. In the future, I would like to focus partly on applications of these research areas in biology, in particular, population dynamics and genetic evolution.
  Since my PhD in Leiden (1985), I have worked at several Dutch universities: Delft (1985-1991), Utrecht (1991-1994), Nijmegen (1994-2000) and Eindhoven (2000-2005). Since 01/10/2000 I am scientific director of EURANDOM, a European institute for research in the stochastic sciences, located on the campus of TU/e. I will step down on 01/10/2005 and move to Leiden as chair of probability.
  In the past years, I have been actively involved with the strategic development of Dutch mathematics via membership of a number of national committees: NWO advisory board of mathematics (ACW), Royal Academy advisory board of mathematics (ARW), board of Mathematical Research Institute (MRI). In addition, I have been working on a number of international committees, e.g. the Bernoulli Society Committee of Stochastic Sciences Institutes."

• New post-docs

  - Dr. Robin de Jong per January 1, 2005 with Bas Edixhoven

  "Being a former student at the Leiden Mathematical Institute it is a great pleasure for me to return here, now as a post-doc student under the direction of Bas Edixhoven. I did my PhD work at the University of Amsterdam, resulting in my thesis entitled `Explicit Arakelov geometry'. I plan to continue to work on explicit aspects of arithmetic algebraic geometry. In particular I plan to continue to work together with Bas on his project dealing with the efficient computation of coefficients of modular forms. During the new semester I will teach a bachelor's course on Topology."

• New Ph.D. students

  - Willem-Jan Palenstijn per April 1, 2004 with Peter Stevenhagen en Bart de Smit

  - Georgia Hadjicharalambous per May 1, 2004 with Sara van de Geer

  "Dear all,
  I am a PhD student of Sara van de Geer and I am also doing research with Erik van Zwet on Estimation of Origin-Destination traffic on a network. Apart from that I am following a Master Course in Utrecht, organized by MRI, in Stochastics in Molecular Biology."

  - Johan Bosman per June 1, 2004 with Bas Edixhoven

  - Michael Muskulus per August 1, 2004 with Sjoerd Verduyn Lunel en Joost Kok (in the framework of the VIEWS-project)

  "I am interested in Mathematical Biology and Natural Computing. Coming from a thereotical physicist's background, I try to apply exact mathematical methods to biological and computer science models, as well as derive new mathematical results from them. My fields of interest are centered around Dynamical Systems, especially Symbolic Dynamics, Ergodic Theory, Probability, Differential Equations on Lattices and Cellular Automata.
  Before coming to Leiden I have been working half a year at the Max Planck Institute for Meteorology, Hamburg, on Cyclone tracking and statistics.
  My motto is: "If I ever conceive any original idea, it will be because I have been abnormally prone to confuse ideas... and have thus found remote analogies and relations which others have not considered! Others rarely make these confusions, and proceed by precise analysis." [from KJW Craik, 'The Nature of Explanation']"

  - Jeanine Daems per November 1, 2004 with Hendrik Lenstra

  - Christian Svensson per February 1, 2005 with Marcel de Jeu and Sergei Silvestrov (Lund)

• Guest of Bart de Smit:

  - Lara Thomas: From January 5-28 she will visit the number theory group to work on her Ph.D. thesis with Bart de Smit.

• Guests of Rob Tijdeman:

  - Attila Bérczes, Lajos Hajdu and Ákos Pintér (Debrecen, Hungary) will visit our institute from January 24-28 on occasion of the thesis defense by Szabolcs Tengely on January 27. On January 25 and 26 they will give some lectures (see above).

Visits/lectures outside our institute

- Peter Stevenhagen: From January 2-19 he will visit David Kohel at the university of Sydney.

- Hendrik Lenstra: On January 16 he will give a lecture, titled "Escher, het ultieme Droste effect" in Paradiso in Amsterdam. This lecture is part of the "Paradisolezingen 2005," organized by the K.L. Poll Stichting together with NWO and the VPRO. For further details, see http://www.verstigt.nl/project.phtml?project=64.