These Proceedings contain selected papers by the speakers invited to the Seminar on Deformations, organized in 1985/87 by Julian tawryno­ wicz (t6dz), whose most fruitful parts took place in 1986 in Lublin during the 3rd Finnish-Polish...

I. Hurwitz-Type Structures.- General Theory.- Editors' note.- Composition of sums of squares with integer coefficients.- Hurwitz-Type Structures Equipped With Additional Geometric and Analytic Structures.- Helmholtz operator with a...