In 1896 A. Sommerfeld published his famous paper 'Zur Theorie der Diffraktion' in vol. 47 of the 'Mathematische Annalen'. His investigations initiated the study of boundary value problems in scattering theory. A long series of research works on general mixed boundary value problems sprang up then. Boundary integral equations together with the Wiener-Hopf method have been generalized and are now a basis for analytical and numerical studies by many mathematicians and engineers working on wave diffraction problems. Commemorating the centenary of Sommerfeld's paper, the aim of this conference is to join the experts and young researchers to present surveys and new results.