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Let $X$ be a complex smooth projective threefold of general type. Assume $q(X)>0$. We show that the $m$-canonical map of $X$ is birational for all $m\geq 5$.

Algebraic Geometry · Mathematics 2020-06-17 Jheng-Jie Chen , Jungkai Alfred Chen , Meng Chen , Zhi Jiang

Let $X$ be a projective minimal Gorenstein 3-fold of general type with canonical singularities. We prove that the 5-canonical map is birational onto its image.

Algebraic Geometry · Mathematics 2007-05-23 Jungkai A. Chen , Meng Chen , De-Qi Zhang

We prove that for all nonsingular projective 3-folds of general type with third plurigenus $P_3 \geq 2$, the pluricanonical map $\varphi_m$ is birational onto its image for all $m \geq 14$, which is optimal.

Algebraic Geometry · Mathematics 2024-12-13 Yong Hu , Jianshi Yan

In this paper we will prove that for a threefold of general type and large volume the second plurigenera is positive and the fifth canonical map is birational.

Algebraic Geometry · Mathematics 2007-10-02 Gueorgui Todorov

In this paper we prove that for any smooth projective variety of Albanese fiber dimension two and of general type, the 6-canonical map is birational. And we also show that the 5-canonical map is birational for any such variety with some…

Algebraic Geometry · Mathematics 2014-02-25 Hao Sun

This paper aims to improve a theorem of Janos Kollar. For a given Complex projective threefold X of general type, suppose the plurigenus p_k(X)\ge 2, Kollar proved that the (11k+5)-canonical map is birational. Here we show that either the…

Algebraic Geometry · Mathematics 2007-05-23 Meng Chen

In this article we present a 3-dimensional analogue of a well-known theorem of E. Bombieri (in 1973) which characterizes the bi-canonical birationality of surfaces of general type. Let $X$ be a projective minimal 3-fold of general type with…

Algebraic Geometry · Mathematics 2007-05-23 Meng Chen , De-Qi Zhang

We prove that for a smooth projective irregular $3$-fold $X$ with $K_X\equiv 0$ and a nef and big divisor $L$ on $X$, $|mL+P|$ gives a birational map for all $m\geq 3$ and all $P\in \text{Pic}^0(X)$. We also use the same method to deal with…

Algebraic Geometry · Mathematics 2016-11-22 Chen Jiang

We study the canonical stability of a smooth projective 3-fold $V$ of general type. We prove that (1) $|5K_V|$ gives a birational map onto its image provided the geometric genus $p_g\geq 4$; (2) $|6K_V|$ gives a birational map provided…

Algebraic Geometry · Mathematics 2007-05-23 Meng Chen

We prove that for any smooth projective $3$-fold of general type with canonical volume greater than $12^6$, the image of its bicanonical map has dimension at least $2$. We also study pluricanonical maps of $3$-folds of general type with…

Algebraic Geometry · Mathematics 2026-05-19 Chen Jiang , Ziqi Liu

We explicitly find lower bounds on the volume of threefolds and fourfolds of general type in order to have nonvanishing of pluricanonical systems and birationality of pluricanonical maps. In the case of threefolds of large volume, we also…

Algebraic Geometry · Mathematics 2011-12-23 Lorenzo Di Biagio

We classify minimal projective 3-folds of general type with $p_g = 2$ by studying the birationality of their 6-canonical maps.

Algebraic Geometry · Mathematics 2019-01-25 Meng Chen , Yong Hu , Matteo Penegini

In this paper we study pluricanonical maps of minimal projective 3-folds of general type with geometric genus $1$, $2$ and $3$. We go in the direction pioneered by Enriques and Bombieri, and other authors, pinning down, for low projective…

Algebraic Geometry · Mathematics 2020-10-07 Meng Chen , Yong Hu , Matteo Penegini

Let $V$ be a complex nonsingular projective 3-fold of general type. We prove $P_{12}(V):=\text{dim} H^0(V, 12K_V)>0$ and $P_{m_0}(V)>1$ for some positive integer $m_0\leq 24$. A direct consequence is the birationality of the pluricanonical…

Algebraic Geometry · Mathematics 2009-11-09 Jungkai A. Chen , Meng Chen

Let $V$ be a complex nonsingular projective 3-fold of general type with $\chi(\omega_V)\geq 0$ (resp. $>0$). We prove that the m-canonical map $\Phi_{|mK_V|}$ is birational onto its image for all $m\ge 14$ (resp. $\geq 8$). Known examples…

Algebraic Geometry · Mathematics 2007-10-23 Meng Chen , Kang Zuo

We show that, for nonsingular projective 4-folds V of general type with geometric genus $p_g\geq 2$, the 33-canonical map is birational onto the image and the canonical volume has the lower bound $1/520$, which improves a previous theorem…

Algebraic Geometry · Mathematics 2021-01-19 Jianshi Yan

Let $V$ be a complex nonsingular projective 3-fold of general type. We shall give a detailed classification up to baskets of singularities on a minimal model of $V$. We show that the $m$-canonical map of $V$ is birational for all $m\geq 73$…

Algebraic Geometry · Mathematics 2010-05-18 Jungkai A. Chen , Meng Chen

We study canonical and pluricanonical maps of varieties isogenous to a product of curves, i.e., quotients of the form $X = (C_1 \times \dots \times C_n)/G$ with $g(C_i)\ge 2$ and $G$ acting freely. For this purpose, we provide a technical…

Algebraic Geometry · Mathematics 2026-03-03 Massimiliano Alessandro , Davide Frapporti , Christian Gleissner

Let $S$ be a nonsingular minimal complex projective surface of general type and the canonical map of $S$ is generically finite. Beauville showed that the geometric genus of the image of the canonical map is vanishing or equals the geometric…

Algebraic Geometry · Mathematics 2016-12-30 Rong Du

This paper proves that the 5-canonical map of a smooth minimal 3-fold is birational when the geometric genus is bigger than 2. A combination of the results in this paper and that of Ein-Lazarsfeld-Lee, the possible exceptional cases are…

Algebraic Geometry · Mathematics 2016-09-07 Meng Chen
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