Đề tài " The Brjuno function continuously estimates the size of quadratic Siegel disks "

If α is an irrational number, Yoccoz defined the Brjuno function Φ by Φ(α) =
n≥0 α0α1 · · · αn−1 log 1 αn , where α0 is the fractional part of α and αn+1 is the fractional part of 1/αn. The numbers α such that Φ(α)