Invited speakers

Pierre Alquier


Dömötör Pálvölgyi
(Eötvös Loránd University)
News about the chromatic number of the plane

At least how many colors do we need to color all the points of the plane such that every pair of points at unit distance receive different colors? This question is known as the Hadwiger-Nelson problem and until one year ago it was only known that 4 colors are needed and 7 are enough. Then in April 2018 gerontologist de Grey showed in a breakthrough result that 4 colors are not enough. His proof was computer assisted, and a collaborative Polymath project was started to find a human-verifiable proof. I will give a short introduction to the classical results, then talk about the current ongoing research with plenty of open problems.

Schedule (provisional)

9h30-11hPierre Alquier
12h-13h30Dömötör Pálvölgyi


Monika Csikos and Nabil H. Mustafa (LIGM, ESIEE Paris). The workshop is supported by ANR grant SAGA.


CouprieMichelESIEE / LIGM
MeunierFrédéricEcole des Ponts ParisTech
De LoeraJesusUniversity of California
DuttaKunalINRIA Sophia-Antipolis
JartouxBruno LIGM, ESIEE Paris
MustafaNabil H. LIGM, ESIEE Paris
BárányImreRényi Institute of Mathematics & UCL
BarbudoEliasESIEE Paris
Dias da FonsecaGuilhermeUniversité Clermont Auvergne
AndresHervéEcole des Ponts ParisTech
ChuChengbinESIEE Paris
De AlbuquerqueArnaldoUFMG and ESIEE Paris
FradeliziMatthieuUniversité Paris-Est Marne-la-Vallée
HubardAlfredoUniversité Paris-Est Marne-la-Vallée