Veronese varieties contained in hypersurfaces

Jason Michael Starr

Published 2017-03-09Version 1

Alex Waldron proved that for sufficiently general degree $d$ hypersurfaces in projective $n$-space, the Fano scheme parameterizing $r$-dimensional linear spaces contained in the hypersurface is nonempty precisely for the degree range $n\geq N_1(r,d)$ where the "expected dimension" $f_1(n,r,d)$ is nonnegative, in which case $f_1(n,r,d)$ equals the (pure) dimension. Using work by Gleb Nenashev, we prove that for sufficiently general degree $d$ hypersurfaces in projective $n$-space, the parameter space of $r$-dimensional $e$-uple Veronese varieties contained in the hypersurface is nonempty of pure dimension equal to the "expected dimension" $f_e(n,r,d)$ in a degree range $n\geq \widetilde{N}_e(r,d)$ that is asymptotically sharp. Moreover, we show that for $n\geq 1+N_1(r,d)$, the Fano scheme parameterizing $r$-dimensional linear spaces is irreducible.