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We give a simple, combinatorial construction of a unital, spherical, non-degenerate $\ast$-planar algebra over the ring $\mathbb{Z}[q^{1/2},q^{-1/2}]$. This planar algebra is similar in spirit to the Temperley-Lieb planar algebra, but…

Geometric Topology · Mathematics 2015-11-06 Lawrence Roberts

Let X be a compact connected Kaehler manifold such that the holomorphic tangent bundle TX is numerically effective. A theorem of Demailly, Peternell and Schenider says that there is a finite unramified Galois covering M --> X, a complex…

Complex Variables · Mathematics 2011-03-21 Indranil Biswas , Ugo Bruzzo

This paper gives two new combinatorial topological proofs of the classification of rational tangles. Each proof rests on an elegant lemma showing that rational tangles are isotopic to canonical alternating rational tangles. The first proof…

Geometric Topology · Mathematics 2009-09-29 Louis H. Kauffman , Sofia Lambropoulou

We study various generalisations of rationally connected varieties, allowing the connecting curves to be of higher genus. The main focus will be on free curves $f:C\to X$ with large unobstructed deformation space as originally defined by…

Algebraic Geometry · Mathematics 2016-03-09 Frank Gounelas

We show that an everywhere regular foliation $\mathcal F$ with compact canonically polarized leaves on a quasi-projective manifold $X$ has isotrivial family of leaves when the orbifold base of this family is special. By a recent work of…

Algebraic Geometry · Mathematics 2017-09-22 Ekaterina Amerik , Frédéric Campana

A $\mathbb Q$-conic bundle is a proper morphism from a threefold with only terminal singularities to a normal surface such that fibers are connected and the anti-canonical divisor is relatively ample. We study the structure of $\mathbb…

Algebraic Geometry · Mathematics 2010-04-26 Shigefumi Mori , Yuri Prokhorov

This paper is devoted to rigidity of smooth bundles which are equipped with fiberwise geometric or dynamical structure. We show that the fiberwise associated sphere bundle to a bundle whose leaves are equipped with (continuously varying)…

Dynamical Systems · Mathematics 2014-07-30 F. Thomas Farrell , Andrey Gogolev

We prove a complete classification of degree-$2$ foliations on $\mathbb{P}^n$ in any dimension, assuming they are not algebraically integrable. If $\mathcal{F}$ is such a foliation, then either $\mathcal{F}$ is the linear pull-back of a…

Algebraic Geometry · Mathematics 2026-01-21 Maurício Corrêa , Alan Muniz

We provide a unified framework for proving Reidemeister-invariance and functoriality for a wide range of link homology theories. These include Lee homology, Heegaard Floer homology of branched double covers, singular instanton homology, and…

Geometric Topology · Mathematics 2018-05-04 Adam Saltz

We extend Hacon--M\textsuperscript{c}Kernan's rational chain connectedness theorem to the complex analytic setting. As a consequence, we prove that the fibers of any resolution of singularities of complex analytic kawamata log terminal…

Algebraic Geometry · Mathematics 2026-03-06 Osamu Fujino

The main result of this paper is a structural theorem for projective Q-factorial toric varieties X in P^N, covered by lines. We prove that there exists a toric fibration f: X -> Z, locally trivial in the Zariski topology, with fiber a…

Algebraic Geometry · Mathematics 2007-05-23 C. Casagrande , S. Di Rocco

We prove a conjecture of V. V. Shokurov which in particular implies that the fibers of a resolution of a variety with divisorial log terminal singularities are rationally chain connected.

Algebraic Geometry · Mathematics 2007-05-23 Christopher D Hacon , James McKernan

It is a conjecture of Koll\'ar that a variety $X$ with rational singularities in some open subvariety $U$ has a rationalification; that is, a proper, birational morphism $f: Y \rightarrow X$ such that $Y$ has rational singularities, and…

Algebraic Geometry · Mathematics 2015-03-24 Jeremy Berquist

This is the first of a series of papers where we relate tangent cones of Hermitian-Yang-Mills connections at an isolated singularity to the complex algebraic geometry of the underlying reflexive sheaf, when the sheaf is locally modelled on…

Differential Geometry · Mathematics 2020-12-22 Xuemiao Chen , Song Sun

In this paper we describe the fundamental group-scheme of a proper variety fibered over an abelian variety with rationally connected fibers over an algebraically closed field. We use old and recent results for the Nori fundamental…

Algebraic Geometry · Mathematics 2020-04-10 Rodrigo Codorniu Cofré

In view of Mori theory, rational homogenous manifolds satisfy a recursive condition: every elementary contraction is a rational homogeneous fibration and the image of any elementary contraction also satisfies the same property. In this…

Algebraic Geometry · Mathematics 2016-05-17 Akihiro Kanemitsu

Let U be an open subset of a unirational variety (or more generally of a separably rationally connected variety). We prove that there is rational curve C in U such that the fundamental group of C surjects onto the fundamental group of U.…

Algebraic Geometry · Mathematics 2007-05-23 János Kollár

We show that polarized endomorphisms of rationally connected threefolds with at worst terminal singularities are equivariantly built up from those on Q-Fano threefolds, Gorenstein log del Pezzo surfaces and P^1. Similar results are obtained…

Algebraic Geometry · Mathematics 2019-02-20 De-Qi Zhang

We prove that the link of a complex normal surface singularity is an L--space if and only if the singularity is rational. This via a recent result of Hanselman, J. Rasmussen, S. D. Rasmussen and Watson (proving the conjecture of Boyer,…

Geometric Topology · Mathematics 2015-10-27 András Némethi

We show that $\mathbb A^1$-connectedness of a large class of varieties over a field $k$ can be characterized as the condition that their generic point can be connected to a $k$-rational point using (not necessarily naive) $\mathbb…

Algebraic Geometry · Mathematics 2021-08-20 Chetan Balwe , Amit Hogadi , Anand Sawant