Singularities of non-degenerate 2-ruled hypersurfaces in 4-space.
The author studies singularities of 2-ruled hypersurfaces in the 4-dimensional Euclidean space. In Section 2 non-degenerate 2-ruled hypersurfaces as an analogue of classical noncylindrical ruled surfaces are defined and studied. The main result of the paper is contained in Theorem 2.5 and its proof is given in Section 4. In Section 5 the author defines almost non-degenerate 2-ruled hypersurfaces which are generic in the usual sense and are non-degenerate almost everywhere. It is shown that the set of 2-ruled hypersurfaces whose map germ at any point is right-left equivalent to the cross cap \(X\) interval or an immersion germ contains an open and dense subset of the space of 2-ruled hypersurfaces.
scientific article; zbMATH DE number 1874216