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We prove the boundedness of $n$-complements for surface pairs in a generalized case without restrictions on multiplicities or the Fano type assumption.

Algebraic Geometry · Mathematics 2023-05-31 Xiangze Zeng

Refining an argument of the second author, we improve the known bounds for the number of rational points near a submanifold of $\mathbb{R}^d$ of intermediate dimension under a natural curvature condition. Furthermore, in the codimension $2$…

Number Theory · Mathematics 2025-12-30 Jonathan Hickman , Rajula Srivastava , James Wright

The notion of 'slope rational connectedness' is introduced in the context of smooth orbifold pairs. The main result parallels the characterization of the rational connectedness of projective manifolds in terms of either the non-existence of…

Algebraic Geometry · Mathematics 2016-07-28 Frederic Campana , Mihai Paun

We describe the resolution of singularities of a threefold which has minimal Picard number. We describe the relation between this minimal resolution and an arbitrary resolution of singularities.

Algebraic Geometry · Mathematics 2023-04-19 Hsin-Ku Chen

In this note we give a p-adic proof of Hodge symmetry for smooth, projective threefolds over complex numbers.

Algebraic Geometry · Mathematics 2013-06-14 Kirti Joshi

In this paper the notion of rational simple connectedness for the quintic Fano threefold $V_5\subset \mathbb{P}^6$ is studied and unirationality of the moduli spaces $\overline{M}_{0,0}^{\text{bir}}(V_5,d)$, with $d \ge 1$, is proved. Many…

Algebraic Geometry · Mathematics 2019-01-23 Andrea Fanelli , Laurent Gruson , Nicolas Perrin

We effectively bound T-singularities on non-rational projective surfaces with an arbitrary amount of T-singularities and ample canonical class. This fully generalizes the previous work for the case of one singularity, and illustrates the…

Algebraic Geometry · Mathematics 2024-04-10 Fernando Figueroa , Julie Rana , Giancarlo Urzúa

We verify the Morrison--Kawamata conjecture for a certain class of rational threefolds, namely blowups of P^3 in the base locus of a net of quadrics with no reducible members. This seems to be the first verified case of the conjecture for…

Algebraic Geometry · Mathematics 2009-11-02 Artie Prendergast-Smith

We prove Simon's conjecture for 3-manifolds.

Group Theory · Mathematics 2018-11-08 Rita Gitik

Let W be a compact simply connected triangulated manifold with boundary and $K \subset W$ be a subpolyhedron. We construct an algebraic model of the rational homotopy type of the complement $W \setminus K$ out of a model of the map of pairs…

Algebraic Topology · Mathematics 2015-05-20 Hector Cordova Bulens , Pascal Lambrechts , Donald Stanley

Let T be a triangulation of S^3 containing a link L in its 1-skeleton. We give an explicit lower bound for the number of tetrahedra of T in terms of the bridge number of L. Our proof is based on the theory of almost normal surfaces.

Geometric Topology · Mathematics 2014-11-11 Simon A King

We provide an easily verifiable condition for local $k$-connectedness of an inverse limit of polyhedra.

General Topology · Mathematics 2019-02-19 G. C. Bell , A. Nagórko

We show that the notion of ribbon rational homology cobordism yields a partial order on the set of aspherical $3$-manifolds, thus supporting a conjecture formulated by Daemi, Lidman, Vela-Vick and Wong. Our proof is built on Agol's recent…

Geometric Topology · Mathematics 2025-10-23 Marius Huber

We study rationality problems for smooth complete intersections of two quadrics. We focus on the three-dimensional case, with a view toward understanding the invariants governing the rationality of a geometrically rational threefold over a…

Algebraic Geometry · Mathematics 2019-04-22 Brendan Hassett , Yuri Tschinkel

We prove the a priori bounds for infinitely renormalizable quadratic polynomials for which we can find an infinite sequence of primitive renormalizations such that the ratios of the periods of successive renormalizations is bounded. This…

Dynamical Systems · Mathematics 2024-01-01 Jeremy Kahn

We study the Noether-Lefschetz locus of a very ample line bundle L on an arbitrary smooth threefold Y. Building on results of Green, Voisin and Otwinowska, we give explicit bounds, depending only on the Castelnuovo-Mumford regularity…

Algebraic Geometry · Mathematics 2007-05-23 Angelo Felice Lopez , Catriona Maclean

We calculate the intersection ring of three-dimensional graph manifolds with rational coefficients and give an algebraic characterization of these rings when the manifold's underlying graph is a tree. We are able to use this…

Geometric Topology · Mathematics 2015-03-23 Margaret I. Doig , Peter D. Horn

We construct orbifolds with quasitoric boundary and show that they have stable almost complex structure. We show that a quasitoric orbifold is complex cobordant to finite disjoint copies of complex orbifold projective spaces. Finally some…

Algebraic Topology · Mathematics 2016-02-01 Soumen Sarkar

We study the spaces of rational curves on Fano threefolds with Gorenstein terminal singularities. We generalize the results regarding Geometric Manin's Conjecture for smooth Fano threefolds, including the classification of subvarieties with…

Algebraic Geometry · Mathematics 2025-05-23 Fumiya Okamura

The boundary of every relatively compact Stein domain in a complex manifold of dimension at least two is connected. No assumptions on the boundary regularity are necessary. The same proofs hold also for $q$-complete domains, and in the…

Complex Variables · Mathematics 2024-07-17 Rafael B. Andrist