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We discuss the birational geometry of singular surfaces in positive characteristic. More precisely, we establish the minimal model program and the abundance theorem for Q-factorial surfaces and for log canonical surfaces. Moreover, in the…

Algebraic Geometry · Mathematics 2015-03-17 Hiromu Tanaka

We prove that if $(X, B+\mathbf{M})$ is a generalized klt pair with $K_X+B+\mathbf{M}_X$ nef and abundant, then $K_X+B+\mathbf{M}_X$ is semiample. More generally, we prove a generalized basepoint free theorem for generalized klt pairs.

Algebraic Geometry · Mathematics 2023-04-18 Priyankur Chaudhuri

We prove an invariance of plurigenera for some foliated surface pairs of general type.

Algebraic Geometry · Mathematics 2019-09-20 Jihao Liu

In this revised form, the proof of the principal lemma has been simplified and the main theorem has been extended to all characteristics for those varieties which are smooth in codimension one. This principal theorem essentially says the…

alg-geom · Mathematics 2009-09-25 J. Alexander , A. Hirschowitz

We construct smooth families of elliptic surface pairs with terminal singularities over a DVR of positive or mixed characteristic $(X,B)\to \mathrm{Spec}R$, such that $P_m(X_k,B_k)>P_m(X_K,B_K)$ for all sufficiently divisible $m>0$. In…

Algebraic Geometry · Mathematics 2022-06-07 Iacopo Brivio

We prove existence of flips, special termination, the base point free theorem and, in the case of log general type, the existence of minimal models for F-dlt foliated pairs of co-rank one on a $\mathbb Q$-factorial projective threefold. As…

Algebraic Geometry · Mathematics 2025-09-05 Paolo Cascini , Calum Spicer

We apply a conjectured inequality on third chern classes of stable two-term complexes on threefolds to Fujita's conjecture. More precisely, the inequality is shown to imply a Reider-type theorem in dimension three which in turn implies that…

Algebraic Geometry · Mathematics 2013-07-16 Arend Bayer , Aaron Bertram , Emanuele Macri , Yukinobu Toda

We prove the finiteness of $B$-representations of generalised log canonical pairs. As a consequence, we prove that, the (relative) abundance for a generalised semi-log canonical pair is implied by the abundance for its normalisation.…

Algebraic Geometry · Mathematics 2021-03-23 Zhengyu Hu

In this text we signal a serious gap in the proof of the main theorem of our paper and explain which parts of the statement remain valid. In fact, the main theorem remains valid unless possibly the variety does not admit…

Algebraic Geometry · Mathematics 2023-04-21 Frédéric Campana , Andreas Höring , Thomas Peternell

We give the multiplicity of terminal singularities on threefolds by simple calculation. Then we obtain the best inequalities for the multiplicity and the index. By using this, we can improve the boundedness number of terminal weak Q-Fano…

Algebraic Geometry · Mathematics 2007-05-23 Nobuyuki Kakimi

In this article we show that if $(X, \Delta)$ is a log canonical compact K\"ahler threefold pair such that $K_X+\Delta$ is nef and the numerical dimension $\nu(X, K_X+\Delta)=2$, then $K_X+\Delta$ is semi-ample. This result combined with…

Algebraic Geometry · Mathematics 2025-06-13 Omprokash Das , Wenhao Ou

We prove several bounds on the number of incidences between two sets of multivariate polynomials of bounded degree over finite fields. From these results, we deduce bounds on incidences between points and multivariate polynomials, extending…

Combinatorics · Mathematics 2025-09-23 Chong Shangguan , Yulin Yang , Tao Zhang

We show that if $(X_t,\mathcal{F}_t)_t$ is a family of foliations with reduced singularities on a smooth family of surfaces, then invariance of plurigenera holds for sufficiently large $m$. On the other hand, we provide examples on which…

Algebraic Geometry · Mathematics 2015-12-03 Paolo Cascini , Enrica Floris

We provide a detailed proof of the validity of the Minimal Model Program for threefolds over excellent Dedekind separated schemes whose residue fields do not have characteristic 2 or 3.

Algebraic Geometry · Mathematics 2022-01-21 Lingyao Xie , Qingyuan Xue

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

We prove for residually finite groups the following long standing conjecture: the number of twisted conjugacy classes of an automorphism of a finitely generated group is equal (if it is finite) to the number of finite dimensional…

Group Theory · Mathematics 2012-05-01 Alexander Fel'shtyn , Evgenij Troitsky

In this paper, we prove the abundance theorem for numerically trivial canonical divisors on strongly $F$-regular varieties, assuming that the geometric generic fibers of the Albanese morphisms are strongly $F$-regular.

Algebraic Geometry · Mathematics 2022-04-19 Sho Ejiri

The Abundance conjecture predicts that on a minimal projective klt pair $(X,\Delta)$, the adjoint divisor $K_X+\Delta$ is semiample. When $\chi(X,\mathcal O_X)\neq0$, we give a necessary and sufficient condition for the conjecture to hold…

Algebraic Geometry · Mathematics 2024-06-27 Vladimir Lazić

In terms of the number of triangles, it is known that there are more than exponentially many triangulations of surfaces, but only exponentially many triangulations of surfaces with bounded genus. In this paper we provide a first geometric…

Combinatorics · Mathematics 2018-05-10 Karim Adiprasito , Bruno Benedetti

In [AGRS] a multiplicity one theorem is proven for general linear groups, orthogonal groups and unitary groups ($GL, O,$ and $U$) over $p$-adic local fields. That is to say that when we have a pair of such groups $G_n\subseteq G_{n+1}$, any…

Representation Theory · Mathematics 2021-06-01 Dor Mezer