activity
20232026
collaborators

6 papers

math.AG2026

On the gap between the integral and rational Gongyo indices of toric Fano varieties

Hiroshi Sato

Exact calculations for smooth toric Fano varieties in dimensions at most seven suggest a sharp dimension-dependent lower bound for the positive difference between the rational and…

math.AG2026

An affine local criterion for toric projective space bundles

Osamu Fujino, Hiroshi Sato

We study when an equidimensional toric morphism is forced to be a projective-space bundle. Our main result is an affine rigidity theorem: if the base space is affine, the toric rel…

math.AG2026

Non-projective complete log canonical surfaces

Osamu Fujino, Nao Moriyama, Hiroshi Sato

We construct non-projective complete log canonical algebraic surfaces whose canonical divisor is semi-ample over any algebraically closed field other than the algebraic closure of…

math.AG2024

On non-projective complete toric varieties

Osamu Fujino, Hiroshi Sato

For every complete toric variety, there exists a projective toric variety which is isomorphic to it in codimension one. In this paper, we show that every smooth non-projective comp…

math.AG2024

On toric foliated pairs

Osamu Fujino, Hiroshi Sato

We discuss lengths of extremal rational curves, Fujita's freeness, and the Kodaira vanishing theorem for log canonical toric foliated pairs.

math.AG2023

A remark on toric foliations

Osamu Fujino, Hiroshi Sato

If a toric foliation on a projective Q-factorial toric variety has an extremal ray whose length is longer than the rank of the foliation, then the associated extremal contraction i…