This volume is dedicated to the eminent Georgian mathematician Roland Duduchava on the occasion of his 70th birthday. It presents recent results on Toeplitz, Wiener-Hopf, and pseudodifferential operators, boundary value problems, operator theory, approximation theory, and reflects the broad spectrum of Roland Duduchava's research. The book is addressed to a wide audience of pure and applied mathematicians.

Roland Duduchava.- The Duduchava-Roch formula.- Convolution Type Operators with Symmetry in Bessel Potential Spaces.- On Symmetries of the Feinberg-Zee Random Hopping Matrix.- Inequalities of BabuSka-Aziz and Friedrichs-Velte for differential forms.- High Frequency Oscillations of first Eigenmodes in Axisymmetric shells as the thickness tends to zero.- Kernels of Wiener-Hopf plus Hankel operators with matching generating functions.- Spline Galerkin methods for the double layer potential equations on contours with corners.- C*-algebras of Bergman Type Operators with Piecewise Continuous Coefficients over Bounded Polygonal Domains.- Solvability and Lyapunov stability of a two-component system of generalized Poisson-Nernst-Planck equations.- A local uniqueness result for a quasi-linear heat transmission problem in a periodic two-phase dilute composite.- The method of potential operators for anisotropic Helmholtz operators on domains with smooth unbounded boundaries.- Gabor Analysis for Schrödinger Equations and Propagation of Singularities.- Commutative algebras of Toeplitz operators on a Siegel domain associated with the nilpotent group of its biholomorphisms.