Old and New Results on the Furstenberg Sets
摘要
This paper is a complement to (Fan et al. in Enseign Math 70:61–120, 2024 [21]). It surveys the works on the Furstenberg set \(S=\{2^{m}3^{n}: m\ge 0, n\ge 0\}\) and its random version T. We also present some new results. For example, it is proved that T almost surely contains a subset of positive lower density which is \(\frac{4}{3}\) -Rider. It is also proved that a class of random sets of integers are Sidon sets as soon as Bourgain’s condition is not satisfied; this generalizes a result of Kahane-Katznelson. Some open questions about S and T are listed at the end of the paper.