Published online by Cambridge University Press: 20 November 2018
In 1927 van der Waerden [6] proved that given positive integers k and l, there exists an integer W such that if 1, 2, …, W are partitioned into k or fewer classes, then at least one class contains an l-term arithmetic progression (l-progression). Let W(k, l), be the smallest such integer W. It would be of interest to find a reasonable upper estimate for W(k, l), say one that could be written down.