... in honor of the 75th birthday of Yurii Reshetnyak, an outstanding mathematician, a member of the Russian Academy of Science.Pref.

Includes bibliographical references.

On an extremal property of quadrilaterals in an Aleksandrov space of curvature leq K ; On boundedness of the fractional maximal operator from complementary Morreytype spaces to Morreytype spaces ; Generalized condensers and distortion theorems for conformal mappings of planar domains ; Rearrangement invariant envelopes of generalized Besov, Sobolev, and Calderon spaces ; Null Lagrangians, the art of integration by parts ; Geometric measure theory formulas on rectifiable metric spaces ; Stability and regularity of solutions to elliptic systems of partial differential equations ; Removable singularities of differential forms and olutions ; Various generalizations of the volume conjecture ; Gradient Young measures and applications to optimal design ; Wavelets for the cochlea ; Sobolevtype classes of mappings with values in metric spaces ; Counterexamples to elliptic regularity and convex integration ; Geometry of CarnotCaratheodory spaces and differentiability of mappings ; Foundations of the theory of mappings with bounded distortion on Carnot groups I D Berg and I G Nikolaev ; V I Burenkov H V Guliyev and V S Guliyev ; V N Dubinin and D B Karp ; M L Goldman ; Tadeusz Iwaniec ; Maria Karmanova ; A P Kopylov ; V M Miklyukov ; Hitoshi Murakami ; P Pedregal ; H M Reimann ; Yu G Reshetnyak ; Laszlo Szekelyhidi Jr ; S K Vodopyanov ; S K Vodopyanov