Abstract
Given a quasisymmetric self-homeomorphismh of the unit circleS 1, letQ(h) be the set of all quasiconformal mappings with the boundary correspondenceh. In [1], it was shown that there existsh for which no extremal extension inQ(h) as a Teichmüller mapping is possible. This disproved some conjectures of long standing. In the example constructed there, the boundary correspondence has a single extremal quasiconformal extension. We show that even when there are infinitely many extremal extensions of the boundary values, it may still happen that none of the extensions is a Teichmüller mapping. An infinitesimal version of this result is also obtained.
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The research was supported by the China Postdoctoral Science Foundation and by the National Natural Science Foundation of China (Grant No. 10401036).
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Yao, G. Is there always an extremal Teichmüller mapping?. J. Anal. Math. 94, 363–375 (2004). https://doi.org/10.1007/BF02789054
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DOI: https://doi.org/10.1007/BF02789054