Liu, Lixing On new symmetrization of rings in space. (Chinese. English summary) Zbl 0789.30010 J. Fudan Univ., Nat. Sci. 31, No. 4, 434-440 (1992). f new symmetrization for rings in the plane is established, which contains the spherical symmetrization of F. W. Gehring as a special case. By making use of the new symmetrization, an extremal problem for rings in space is solved. Reviewer: Li Zhong (Beijing) MSC: 30C80 Maximum principle, Schwarz’s lemma, Lindelöf principle, analogues and generalizations; subordination Keywords:symmetrization PDFBibTeX XMLCite \textit{L. Liu}, J. Fudan Univ., Nat. Sci. 31, No. 4, 434--440 (1992; Zbl 0789.30010)