Type: Article
Publication Date: 2017-01-01
Citations: 15
DOI: https://doi.org/10.1112/s0025579317000316
Define to be the largest cardinality of a set that does not contain four elements in arithmetic progression. In 1998, Gowers proved that for some absolute constant . In 2005, the authors improved this to In this paper we further improve this to which appears to be the limit of our methods.