Li, Zhong The lower bound of the maximal dilatation of the Beurling-Ahlfors extension. (English) Zbl 0723.30016 Ann. Acad. Sci. Fenn., Ser. A I, Math. 15, No. 1, 75-81 (1990). The author gives an example of a piecewise linear \(\rho\)-quasisymmetric function \((\rho >1)\) such that the corresponding Beurling-Ahlfors extension to the upper halfplane has maximal dilatation \(\geq (2\rho +1)(1-1\sqrt{\rho})\). The result shows that an estimate from above given by Lehtinen is asymptotically sharp as \(\rho\to \infty\). Reviewer: Jochen Becker (Berlin) Cited in 1 Document MSC: 30C62 Quasiconformal mappings in the complex plane Keywords:quasiconformal extension; boundary value problem; quasisymmetric function PDFBibTeX XMLCite \textit{Z. Li}, Ann. Acad. Sci. Fenn., Ser. A I, Math. 15, No. 1, 75--81 (1990; Zbl 0723.30016) Full Text: DOI