arXiv subjects
Publications and source records attributed to Hiroto Akaike.
We classify all normal stable Horikawa surfaces with only $\mathbb{Q}$-Gorenstein smoothable log canonical singularities. Furthermore, we provide a criterion for their global $\mathbb{Q}$-Gorenstein smoothability and describe the boundary strata of the moduli space of $\mathbb{Q}$-Gorenstein smoothable normal stable Horikawa surfaces.
The \textit{slope} of a fibered $3$-folds $f:X \to B$ is a relative numerical invariant defined by $λ(f) := K_{f}^{3}/\mathrm{deg}(f_{\ast}ω_{f})$, where $K_{f}$ is the relative canonical divisor and $ω_{f}$ is the relative dualizing sheaf. Establishing slope inequalities is a fundamental problem in the geography of fibered spaces. In this paper, we introduce a new invariant called the \textit{minimal covering degree} as a gonality-type invariant and study a lower bound of the slope increasing with the covering gonality and the minimal covering degree of the general fiber of $f$.
The delta invariant interprets the criterion for the K-(poly)stability of log terminal Fano varieties. In this paper, we determine the whole local delta invariant for all weak del Pezzo surfaces with the anti-canonical degree $\geq 5$.
We study automorphism groups of fibered surfaces for finite cyclic covering fibrations of an elliptic surface. We estimate the order of a finite subgroup of automorphism groups in terms of the genus of the fiber, the genus of the base curve, the covering degree and the square of the relative canonical divisor.
We study the order of automorphism groups of cyclic covering fibrations of a ruled surface. Arakawa and later Chen studied it for hyperelliptic fibrations and gave the upper bound. The purpose of present paper is to pursue the analog for cyclic covering fibrations.
Let $f:S\to B$ be a finite cyclic covering fibration of a fibered surface. We study the lower bound of slope $λ_{f}$ when the relative irregularity $q_{f}$ is positive.