Sulla seminormalità delle superficie algebriche
In this paper the author proves that a surface \(S\) in \(\mathbb P^4\) is seminormal if and only if its singular points are of the following three types: (1) isolated normal points; (2) isolated double points with tangent cone composed of two planes intersecting in one point; (3) curves \(C\) of points of multiplicity 2 or 3 (generically) and of ``general type'' (roughly, at the generic point of \(C\) the tangent cone is composed of 2, resp. 3, planes with a line in common and otherwise independent). This result proves also that a generic projection in \(\mathbb P^4\) of a non-singular surface (of characteristic 0) is seminormal.
scientific article; zbMATH DE number 3697279