A semigroup variety is called a Cross variety if it is finitely based, is generated by a finite semigroup, and has a finite lattice of subvarieties. It is established in which cases the wreath product of two semigroup varieties each of which is an atom of the lattice of semigroup varieties is a Cross variety. Furthermore, for all the pairs of atoms U and V for which this is possible, either a f...

We prove that a 2-stein submanifold in space form whose normal connection is flat or codimension at most 2, has constant curvature.

We show that the Brill-Noether locus M 18 , 16 3 <mml:annotation...