Willem H. Haemers

I know all decimals of π, only the order is a problem.

Everybody is unique, except me (Theo Maassen).

Major fields
Discrete mathematics, combinatorics, algebraic graph theory, finite geometry, design theory and coding theory.

Homepage maintained by Tilburg University

Spectra of Graphs with Andries E. Brouwer, textbook, Springer Universitext, 2012.
The Beauty of Discrete Mathematics, Asset Magazine 26 (2011) 16-19.
Discreet en Mooi, inaugurele rede (inaugural lecture in Dutch, Sep 4, 2009).
Eigenvalue techniques in design and graph theory, Ph.D. thesis (1979).
An inequaliy for near hexagons with Rudi Mathon, unpublished manuscript, 1979.

Editor (former editor-in-chief) of The Electronic Journal of Combinatorics.
Former editor of Innovations in Incidence Geometry.
Former member of the editorial board of Designs, Codes and Cryptography.
Member of the advisory board of Publications de l'Institut Mathématique (Serbia).

Conferences and workshops
IPM Combinatorics and Computing Conference 2019 (IPMCCC2019), Tehran, Iran, April 16-18, 2019.
Groups and Graphs, Designs and Dynamics, Yichang, China, August 12 - 25, 2019.

Other things and links
Slide show for ILAS conference, Ames, Iowa, USA, July 27, 2017.
Picture of "Spectral characterization of mixed extensions of small graphs".
Reader with Addendum for a series of lectures on "Matrix techniques for strongly regular graphs and related geometries", given in Ghent (April 2000).
Videos of an advanced course on eigenvalue techniques in graph theory given in Barcelona (June 2011).
1. Interlacing; the appetizer. 2. More interlacing for the adjacency matrix. 3. Perfect matchings. 4. Regularity and spectral characterizations.
Aida Abiad, Andries E. Brouwer, Edwin van Dam, Ted Spence.
Fon-Der-Flaass memorial book.
Chello, UvT-mail, Bibliotheek.
Paintings by Katrien Haemers.

Department of Econometrics and Operations Research,
Tilburg University,
P.O. Box 90153,
5000 LE Tilburg,
The Netherlands
Tel. +31-134662777
Fax +31-134663280
E-mail haemers at uvt dot nl