• Contractive inequalities for Bergman spaces and multiplicative Hankel forms 

      Bayart, Frédéric; Brevig, Ole Fredrik; Haimi, Antti; Ortega-Cerdà, Joaquim; Perfekt, Karl-Mikael (Journal article; Peer reviewed, 2019)
      We consider sharp inequalities for Bergman spaces of the unit disc, establishing analogues of the inequality in Carleman's proof of the isoperimetric inequality and of Weissler's inequality for dilations. By contractivity ...
    • Norms of composition operators on the $H^2$ space of Dirichlet series 

      Brevig, Ole Fredrik; Perfekt, Karl-Mikael (Journal article; Peer reviewed, 2020)
      , generated by Dirichlet series symbols φ. We prove two different subordination principles for such operators. One concerns affine symbols only, and is based on an arithmetical condition on the coefficients of φ. The other ...
    • The multiplicative Hilbert matrix 

      Brevig, Ole Fredrik; Perfekt, Karl-Mikael; Seip, Kristian; Siskakis, Aristomenis; Vukotic, Dragan (Journal article; Peer reviewed, 2016)
    • Volterra operators on Hardy spaces of Dirichlet series 

      Brevig, Ole Fredrik; Perfekt, Karl-Mikael; Seip, Kristian (Journal article; Peer reviewed, 2019)
      For a Dirichlet series symbol g.s/ D P n 1 bnn s , the associated Volterra operator Tg acting on a Dirichlet series f .s/ D P n 1 ann s is defined by the integral f 7! Z C1 s f .w/g0 .w/ dw: We show that Tg is a bounded ...