Marcel de Jeu 's home page at Leiden University

Home page of Marcel de Jeu

E-mail address:	Remove `NOBOTSHALLUSETHIS' from mdejeuNOBOTSHALLUSETHIS@math.leidenuniv.nl
Home page:	http://www.math.leidenuniv.nl/~mdejeu/
Postal address:	Mathematical Institute Leiden University P.O. Box 9512 2300 RA Leiden The Netherlands
Visiting address:	Einsteinweg 55 2333 CC Leiden The Netherlands
Office number:	BW 1.11
Office telephone number:	+31 71 527 7118
General telephone number:	+31 71 527 7111
General fax number:	+31 71 527 7101

Additional appointment

Extraordinary professor at the University of Pretoria (Pretoria, South Africa)

Current research interests

Abstract representation theory and harmonic analysis in an ordered context
Ordered vector spaces and algebras
Banach algebras and operator algebras

Publications

Since 2001, I have always uploaded my papers, including a final version with the text as published, to arXiv . The list in MathSciNet (use this link when you are at the Leiden campus) also contains my older papers, but it can be lagging considerably for the newer ones.
The Leiden Repository contains a number of my papers as published.
My ORCID iD is 0000-0002-7295-8969.

PhD students

Christian Svensson (2009, thesis)
Marten Wortel (2012, thesis)
Miek Messerschmidt (2013, thesis; funded by NWO)
Rui Xie (September 2013 - August 2014, visiting PhD student from Harbin Institute of Technology; funded by CSC)
Xingni Jiang (2018, thesis; funded by CSC)
Yang Deng (2021, thesis; funded by CSC)
Walt van Amstel (2024; University of Pretoria; joint with main adviser Jan Harm van der Walt)
Chun Ding (expected 2025; joint with Onno van Gaans; funded by CSC)

Editorships

I am an editor of Positivity.

Positivity conferences

I am the chairman of the steering committee for the biyearly Positivity conferences. Please feel free to contact me for all matters concerned.

Past and upcoming events

Summer School on Noncommutative integration, Leiden, 9 - 13 June 2008.
Workshop Operator structures and dynamical systems, Leiden, 21 - 25 July 2008 (satellite of 5 ECM). The proceedings appeared in 2009 in the Contemporary Mathematics series of the AMS.
The Positivity VII conference was held from 22 - 26 July 2013 at the campus of Leiden Universityl, jointly organised by Leiden University and Delft University of Technology. I served as chairman on the organization committee of this Zaanen Centennial Conference, on the occasion of the 100th birthyear of Adriaan Cornelis Zaanen (1913 - 2003). Edited by Onno van Gaans, Ben de Pagter, Mark Veraar, and myself, the proceedings appeared with Birkhäuser in 2016.
Tony Wickstead and I were the main organisers, together with Garth Dales, Sonja Mouton, and Ben de Pagter, of the Ordered Banach algebra workshop at the Lorentz Center in Leiden, from 21 - 25 July 2014. Tony Wicksteade and I were also the editors of a special issue on ordered Banach algebras of Positivity on the subject that appeared in 2017. It also contains a list of open problems that was compiled by Tony Wickstead, and an obituary for Egor Alekhno, who was one of the participants. On the ocassion of the workshop, Tony Wickead, Sonja Mouton, and I compiled a bibliography on ordered Banach algebras that we believed to be reasonably complete at the time.
Positivity VIII was held in Chengdu from 20 - 24 July 2015.
Positivity IX was held in Edmonton from 17 - 21 July 2017.
In October 2017, Garth Dales was my guest as that year's Kloosterman Professor.
A workshop on operator algebras and harmonic analysis was held at the Tsinghua Sanya International Mathematics Forum from 18 - 22 December 2017.
There was a BIRS workshop on recent advances on Banach lattices in Oaxaca, Mexico, from 29 April - 4 May 2018.
From 26 - 28 September 2018, Jan van Neerven and I organised a workshop `Positivity and noncommutative analysis' in Delft on the occasion of the 65th birthday of Ben de Pagter. A Festschrift for Ben de Pagter, of which I am one of the editors, was also initiated. It appeared with Birkhäuser in 2019.
Positivity X was held in Pretoria from 8 - 12 July 2019.
Conference on Ordered Structures with Applications in Economy and Finance, 3-7 May 2021, online.
Francesca Arici, Rachid El Harti, Dimitris Gerontogiannis, Yuezhao Li, and I organised the 5th Conference of Settat on Operator Algebras and Applications from 9-13 January 2023 in Marrakech, Morocco.
Vladimir Troitsky was the main organiser of the workshop Recent advances in Banach lattices from 7 - 12 May 2023 in Banff, Alberta, Canada. I was one of the co-organisers.
Positivity XI, originally scheduled in July 2021, took place from 10-14 July 2023, still in Ljubljana, Slovenia.
Together with Lei Li, Xingni Jiang, Yunbai Dong and Niushan Gao, I organised the conference Positivity and Banach spaces from 1-5 July 2024 at the Chern Institute of Mathematics in Tianijn, China.
Positivity XII will be fom 2-7 June 2025 in Hammamet, Tunisia.

Functional analysis seminar

We have a series of yearly functional analysis seminars in the spring semester, with staff, postdocs, PhD students, and advanced MSc students as participants, also from outside Leiden.

In the 2005 seminar we concentrated on spectral theory and operator algebras.
The 2006 seminar was about Banach space theory.
In the 2007 seminar the emphasis was on operator theory.
In 2007 - 2008 we covered most of the book by Albiac and Kalton on Banach space theory.
In 2008 - 2009 was devoted to Meyer-Nieberg's book on Banach lattices; the twin seminar in Delft was on noncommutative probability.
In 2009 - 2010 the seminar was based on Kaniuth's `A course in commutative Banach algebras'.
In 2010 - 2011 we used Engel's and Nagel's `A short course on operator semigroups'.
In fall 2011 a joint Leiden/Delft seminar was dedicated to Choquet theory, based on Phelps' book.
In spring 2012, Ryan's `Introduction to tensor products of Banach spaces' was used.
In fall 2012, Miek Messerschmidt ran a seminar on `Cones and duality' by Aliprantis and Tourky.
In spring 2013, Onno van Gaans ran a seminar on `An invitation to operator theory' by Abramovich and Aliprantis.
In spring 2014, Onno van Gaans ran a seminar on the geometry of Banach spaces.
In spring 2015, Onno van Gaans and I organised a seminar on concrete examples of Banach lattices and their (regular) operators.
In spring 2016, Sander Hille, Onno van Gaans, and I organised a seminar on spaces of measures.
In spring 2017, Onno van Gaans and I organised a seminar on partially ordered vector spaces and their operators.
In spring 2018, Onno van Gaans and I organised a seminar on abstract harmonic analysis.
In spring 2019, Onno van Gaans and I organised a seminar on Banach space theory.
In spring 2020, Bram Mesland, Onno van Gaans, and I organised a seminar on operator spaces that had to be discontinued because of covid.
In spring 2021, there was no seminar because of covid.
In fall 2021, Bram Mesland, Jan Harm van der Walt, and I organised a seminar on completely bounded maps and operator algebras.
In spring 2022, Bram Mesland, Onno van Gaans, and I organised a seminar on JB- and JBW-algebras. Our mathematical guides were Mark Roelands and Marten Wortel.
In spring 2023, Bram Mesland, Onno van Gaans, and I organised a seminar on harmonic analysis.
In spring 2024, Mark Roelands ran a seminar on Zaanen's `An introduction to operator theory on Riesz spaces'.

Teaching fall 2024

Onno van Gaans and I are the lecturers of the national Mastermath course in Functional Analysis. We use Conway's `A course in functional analysis'.

Teaching spring 2025

Dirk van der Hoeven and I are the organisers of the bachelor seminar on Analysis, Stochastics, and Optimisation.