title: Distortion of area and dimension under quasiconformal mappings in the plane.
abstract: We find the exact estimates for the distortion of area and Hausdorff dimension under a K-quasiconformal mapping of the complex plane. This solves also the problem of finding the precise bound p(K) of the exponents p such that for each planar K-quasiconformal mapping f the Jacobian Jf is locally p-integrable; it follows that p(K) = 2K/(K - 1). Further consequences include among others the regularity and removability results for quasiregular mappings and sharp estimates for the complex Hilbert transform.
authors.affiliation: Department of Mathematics, University of Helsinki, SF-00014 Helsinki, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Astala