3 papers
math.AG2020
On the relative version of Mori dream spaces
Rikito Ohta
This paper is devoted to a study of the relative version of a Mori dream space (MDS for short), which was first introduced by Andreatta and Wiśnewski and will be called Mori dream…
math.AG2019
On Seshadri constants of non-simple abelian varieties
Rikito Ohta
We prove that the Seshadri constant of a polarized abelian variety is equal to the Seshadri constant of its abelian subvariety if the Seshadri constant is relatively small with res…
math.AG2018
On ruled surfaces with big anti-canonical divisor and numerically trivial divisors on weak log Fano surfaces
Rikito Ohta, Shinnosuke Okawa
We investigate the structure of geometrically ruled surfaces whose anti-canonical class is big. As an application we show that the Picard group of a normal projective surface whose…