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We study a pair consisting of a smooth variety over a field of positive characteristic and a multi-ideal with a real exponent. We prove the finiteness of the set of minimal log discrepancies for a fixed exponent if the dimension is less…

Algebraic Geometry · Mathematics 2025-09-12 Shihoko Ishii

We show that termination of flips for $\mathbb Q$-factorial klt pairs in dimension $r$ implies existence of minimal models for algebraically integrable foliations of rank $r$ with log canonical singularities over a $\mathbb Q$-factorial klt…

Algebraic Geometry · Mathematics 2023-03-15 Paolo Cascini , Calum Spicer

In this paper, we establish a structure theorem for projective klt pairs $(X,\Delta)$ with nef anti-log canonical divisor; specifically, we prove that, up to replacing $X$ with a finite quasi-\'etale cover, $X$ admits a locally trivial…

Algebraic Geometry · Mathematics 2023-08-31 Shin-ichi Matsumura , Juanyong Wang

We discuss the minimal model program for b-log varieties, which is a pair of a variety and a b-divisor, as a natural generalization of the minimal model program for ordinary log varieties. We show that the main theorems of the log MMP work…

We prove that the base space of a log smooth family of log canonical pairs of log general type is of log general type as well as algebraically degenerate, when the family admits a relative good minimal model over a Zariski open subset of…

Algebraic Geometry · Mathematics 2018-11-20 Chuanhao Wei , Lei Wu

We show that many statements of the Minimal Model Program, including the cone theorem, the base point free theorem and the existence of Mori fibre spaces, fail for 1-foliated surface pairs $(X,\mathcal{F})$ with canonical singularities in…

Algebraic Geometry · Mathematics 2024-01-10 Fabio Bernasconi

We construct Mori Dream Spaces as fine moduli spaces of representations of bound quivers, thereby extending results of Craw--Smith \cite{CrawSmith} beyond the toric case. Any collection of effective line bundles $\mathscr{L}=(\mathscr{O}_X,…

Algebraic Geometry · Mathematics 2013-02-26 Alastair Craw , Dorothy Winn

The main result is that a quasi-projective surface has negative log Kodaira dimension (i.e. no log pluricanonical sections) iff it is dominated by images of the affine line. This follows from our main intermediate result, that the smooth…

alg-geom · Mathematics 2008-02-03 Sean Keel , James McKernan

We prove that the log Iitaka conjecture holds for log canonical fibrations when log canonical divisor of a sufficiently general fiber is abundant.

Algebraic Geometry · Mathematics 2019-05-02 Kenta Hashizume

We prove an analogue of Fujino and Mori's ``bounding the denominators'' in the log canonical bundle formula (see also Prokhorov and Shokurov) for Kawamata log terminal pairs of relative dimension one. As an application we prove that for a…

Algebraic Geometry · Mathematics 2008-05-23 Gueorgui Todorov

Given a complex projective manifold $X$ and a divisor $D$ with normal crossings, we say that the logarithmic tangent bundle $T_X(-\log D)$ is R-flat if its pull-back to the normalization of any rational curve contained in $X$ is the trivial…

Algebraic Geometry · Mathematics 2020-08-07 Stéphane Druel , Federico Lo Bianco

Drawing on the theory of Minimal Model Program singularities for foliations, we define relative canonical and log-canonical singularities for algebraic stacks with finite generic stabilisers. We show that if a point has log-canonical…

Algebraic Geometry · Mathematics 2026-03-27 Federico Bongiorno

Let $X$ be a normal projective variety admitting a polarized endomorphism $f$, i.e., $f^*H\sim qH$ for some ample divisor $H$ and integer $q>1$. Then Broustet and Gongyo proposed the conjecture that $X$ is of Calabi-Yau type (CY for short),…

Algebraic Geometry · Mathematics 2025-09-23 Wentao Chang , De-Qi Zhang

We prove that the canonical ring of a smooth projective variety is finitely generated.

Algebraic Geometry · Mathematics 2008-08-14 Caucher Birkar , Paolo Cascini , Christopher D. Hacon , James McKernan

We can run the MMP for any divisor on any $\mathbb{Q}$-factorial projective toric variety. We show that two Mori fiber spaces, which are outputs of the above MMP, are connected by finitely many elementary transforms.

Algebraic Geometry · Mathematics 2022-07-14 Keisuke Miyamoto

We establish the minimal model program for log canonical and Q-factorial surfaces over excellent base schemes.

Algebraic Geometry · Mathematics 2018-01-22 Hiromu Tanaka

We consider pairs (X,A), where X is a variety with klt singularities and A is a formal product of ideals on X with exponents in a fixed set that satisfies the Descending Chain Condition. We also assume that X has (formally) bounded…

Algebraic Geometry · Mathematics 2010-06-25 Tommaso de Fernex , Lawrence Ein , Mircea Mustata

We prove that, assuming the F-conjecture, the log canonical model of the pair $(\bar{M}_{0,n}, \sum a_i \psi_i)$ is the Hassett's moduli space of weighted pointed stable rational curves without any modification of weight coefficients. For…

Algebraic Geometry · Mathematics 2010-11-18 Han-Bom Moon

We first introduce a weak type of Zariski decomposition in higher dimensions: an $\R$-Cartier divisor has a weak Zariski decomposition if birationally and in a numerical sense it can be written as the sum of a nef and an effective…

Algebraic Geometry · Mathematics 2009-07-30 Caucher Birkar

Let $(X,D)$ be an open log del Pezzo surface of rank one, that is, $X$ is a normal projective surface of Picard rank one, the boundary $D$ is a reduced nonzero divisor on $X$, and the anti-log canonical divisor $-(K_X+D)$ is ample. We show…

Algebraic Geometry · Mathematics 2025-08-20 Karol Palka , Tomasz Pełka