Hirokazu Nasu

activity

20052026

most citedObstructions to deforming curves on a 3-fold, I: A generalization of Mumford's example and an application to Hom schemes

7 citations · 17 across the 7 of their papers we have counts for

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9 papers · 1 filter

math.AG2026

Obstructions to deforming space curves lying on a complete intersection of quadrics

Hirokazu Nasu

Let $S = S_{2, \dots, 2} \subset P^{n + 2}$ be a smooth complete intersection of $n$ quadrics containing a line $E$ , where $n \geq 3$ , and set $D = (n - 1) h + E$ , where $\mathbf…

math.AG2025

Obstructions to deforming space curves lying on a del Pezzo surface

Hirokazu Nasu

We study the deformations of space curves $C \subset P^{4}$ , assuming that they are contained in a smooth complete intersection $S_{2, 2} \subset P^{4}$ , i.e., a smooth…

math.AG2019

Obstructions to deforming space curves lying on a smooth cubic surface

Hirokazu Nasu

In this paper, we study the deformations of curves in the projective 3-space $P^{3}$ (space curves), one of the most classically studied objects in algebraic geometry. We pro…

math.AG2019★ 1 cited

Obstructions to deforming curves on an Enriques-Fano 3-fold

Hirokazu Nasu

We study the deformations of a curve $C$ on an Enriques-Fano $3$ -fold $X \subset P^{n}$ , assuming that $C$ is contained in a smooth hyperplane section $S \subset X$ , that is…

math.AG2018★ 2 cited

Obstructions to deforming curves on a prime Fano 3-fold

Hirokazu Nasu

We prove that for every smooth prime Fano $3$ -fold $V$ , the Hilbert scheme $Hilb^{sc} V$ of smooth connected curves on $V$ contains a generically non-reduced irreduc…

math.AG2016★ 6 cited

Obstructions to deforming curves on a 3-fold, III: Deformations of curves lying on a K3 surface

Hirokazu Nasu

We study the deformations of a smooth curve $C$ on a smooth projective threefold $V$ , assuming the presence of a smooth surface $S$ satisfying $C \subset S \subset V$ . Generalizing…

math.AG2006

Obstructions to deforming curves on a 3-fold, II: Deformations of degenerate curves on a del Pezzo 3-fold

Hirokazu Nasu

We study the Hilbert scheme (Hilb V) of smooth connected curves on a smooth del Pezzo 3-fold V. We prove that every degenerate curve C, i.e. every curve contained in a smooth hyper…

math.AG2006★ 7 cited

Obstructions to deforming curves on a 3-fold, I: A generalization of Mumford's example and an application to Hom schemes

Shigeru Mukai, Hirokazu Nasu

We give a sufficient condition for a first order infinitesimal deformation of a curve on a 3-fold to be obstructed. As application we construct generically non-reduced components o…

math.AG2005★ 1 cited

Obstructions to deforming space curves and non-reduced components of the Hilbert scheme

Hirokazu Nasu

Let $H i l b P^{3}$ denote the Hilbert scheme of smooth connected curves in $P^{3}$ . We consider maximal irreducible closed subsets $W \subset H i l b P^{3}$ whose general member $C$ is contai…