Blowup algebras of rational normal scrolls

Abstract

We determine the equations of the blowup of P n \mathbb {P}^{n} along a d d -fold rational normal scroll S \mathcal {S} , and we prove that the Rees ring and special fiber ring of S ⊆ P n \mathcal {S}\subseteq \mathbb {P}^{n} are Koszul algebras.