Equiaffine Darboux frames for codimension 2 submanifolds contained in hypersurfaces (Q1687569)

The authors study affine submanifolds of codimension-2 which are contained in a hypersurface of the affine space. They develop a theory which allows to study such hypersurfaces in a canonical way. Note that this theory is essentially different from the other codimension-2 affine differential geometry theories as developped by Weise and Klingenberg, or Nomizu and Vrancken. The main aim of the paper is to generalize the concept of tangent developable surface of a surface along a curve and to study its singularities.