turkmath.org

In this talk we will be concerned with a tensor product C*-algebra generated by Toeplitz operators with QC(quasi-continuous) symbols and Fourier multipliers acting on the Hardy space of the bi-disc. An exact characteriztion of Fredholmness of certain linear algebraic combination of Toeplitz operators and Fourier multipliers will be given. As an application, an exact characterization of the essential spectrum of a "quasi-parabolic" composition operator acting on the Hardy space of the bi-disc will be given. This is the result of a joint work with B.B. Koca of Istanbul University.