Abstract for the talk on 30.11.2016 (13:30 h)

Seminar on Non-Linear Algebra

Bernd Sturmfels (University of California, Berkeley + MPI MIS, Leipzig)
Real Rank Two Geometry

The real rank two locus of an algebraic variety is the closure of the union of all secant lines spanned by real points. We seek a semi-algebraic description of this set. Its algebraic boundary consists of the tangential variety and the edge variety. Our study of Segre and Veronese varieties yields a characterization of tensors of real rank two. Joint with Anna Seigal.