On the stratification of secant varieties of Veronese varieties via symmetric rank

Abstract

When considering $\sigma_r(X)$, the variety of r-secant $\PP {r-1}$ to a projective variety $X$, one question which arises is what are the possible values of the $X$-rank of points on $\sigma_r(X)$, apart from the generic value $r$? This geometric problem is of particular relevance (also for Applied Math) when $X$ is a variety parameterizing some kind of tensors. We study here the case when $X$ is a Veronese variety (i.e. the case of symmetric tensors). We find the complete description of the rank strata in some cases, and we give algorithms which compute the symmetric rank.