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Let $(M, g, \omega, f, \lambda)$ be a K\"{a}hler gradient Ricci soliton in real dimension four. One first observes that it is an integrable Hamiltonian system in a classical sense. Indeed, all known complete examples are toric and the…

Differential Geometry · Mathematics 2026-01-23 Hung Tran

This paper investigates the question of which smooth compact 4-manifolds admit Riemannian metrics that minimize the L2-norm of the curvature tensor. Metrics with this property are called OPTIMAL; Einstein metrics and scalar-flat…

Differential Geometry · Mathematics 2007-05-23 Claude LeBrun

We investigate compact Kahler manifolds, which are acted on by a semisimple compact Lie group G of isometries with one hypersurface orbit. In case of ordinary action and projectable complex structure, we set up a one to one correspondence…

dg-ga · Mathematics 2008-02-03 F. Podesta' , A. Spiro

We consider locally conformal Kaehler geometry as an equivariant (homothetic) Kaehler geometry: a locally conformal Kaehler manifold is, up to equivalence, a pair (K,\Gamma) where K is a Kaehler manifold and \Gamma a discrete Lie group of…

Differential Geometry · Mathematics 2007-05-23 Rosa Gini , Liviu Ornea , Maurizio Parton , Paolo Piccinni

In this article we study the Hofer geometry of a compact Lie group $K$ which acts by Hamiltonian diffeomorphisms on a symplectic manifold $M$. Generalized Hofer norms on the Lie algebra of $K$ are introduced and analyzed with tools from…

Metric Geometry · Mathematics 2023-02-22 Gabriel Larotonda , Martin Miglioli

We characterize isometric actions on compact Kaehler manifolds admitting a Lagrangian orbit, describing under which condition the Lagrangian orbit is unique. We furthermore give the complete classification of simple groups acting on the…

Differential Geometry · Mathematics 2008-07-18 Lucio Bedulli , Anna Gori

We calculate Chow quotients of some families of symmetric \(T\)-varieties. In complexity two we obtain new examples of K\"ahler-Einstein metrics by bounding the symmetric alpha invariant of their orbifold quotients. As an additional…

Algebraic Geometry · Mathematics 2019-12-20 Jacob Cable

We prove the local classification of K\"ahler metrics with constant holomorphic sectional curvature by exploiting the geometry of the bundle of 1-jets of holomorphic functions.

Differential Geometry · Mathematics 2025-07-30 Martin de Borbon

We prove the equivariant holomorphic Morse inequalities for a holomorphic torus action on a holomorphic vector bundle over a compact Kahler manifold when the fixed-point set is not necessarily discrete. Such inequalities bound the twisted…

dg-ga · Mathematics 2016-08-31 Siye Wu , Weiping Zhang

We propose an operator generalization of the Li-Haldane conjecture regarding the entanglement Hamiltonian of a disk in a 2+1D chiral gapped groundstate. The logic applies to regions with sharp corners, from which we derive several universal…

Strongly Correlated Electrons · Physics 2026-02-06 Xiang Li , Ting-Chun Lin , Yahya Alavirad , John McGreevy

We study nearly-Kahler 6-manifolds equipped with a cohomogeneity-two Lie group action for which the principal orbits are coisotropic. If the metric is complete, then we show that this last condition is automatically satisfied, and both the…

Differential Geometry · Mathematics 2018-10-31 Jesse Madnick

We will discuss in this paper homogeneous locally conformally Keahler (or shortly homogeneous l.c.K.) manifolds and locally homogeneous l.c.K. manifolds from various aspects of study in the field of l.c.K. geometry. We will provide a survey…

Differential Geometry · Mathematics 2016-01-19 Keizo Hasegawa , Yoshinobu Kamishima

Let M be a compact, connected symplectic 2n-dimensional manifold on which an(n-2)-dimensional torus T acts effectively and Hamiltonianly. Under the assumption that there is an effective complementary 2-torus acting on M with symplectic…

Symplectic Geometry · Mathematics 2012-07-06 Yi Lin , Álvaro Pelayo

We call complex quasifold of dimension k a space that is locally isomorphic to the quotient of an open subset of the space C^k by the holomorphic action of a discrete group; the analogue of a complex torus in this setting is called a…

Complex Variables · Mathematics 2007-05-23 Fiammetta Battaglia , Elisa Prato

A torsion-free G_2 structure admitting an infinitesimal isometry is shown to give rise to a 4-manifold equipped with a complex symplectic structure and a 1-parameter family of functions and 2-forms linked by second order equations.…

Differential Geometry · Mathematics 2009-11-10 Vestislav Apostolov , Simon Salamon

We investigate degenerate special-Hermitian metrics on compact complex manifolds, in particular, degenerate K\"ahler and locally conformally K\"ahler metrics on special classes of non-K\"ahler manifolds.

Differential Geometry · Mathematics 2018-02-20 Daniele Angella , Adriano Tomassini

We study the closure of a complex subtorus in a toric manifold. If the closure of the complex subtorus is a smooth complex submanifold in the toric manifold, then the subtorus action on such submanifold is Hamiltonian. In this case, we may…

Symplectic Geometry · Mathematics 2025-08-14 Kentaro Yamaguchi

Suppose given a Hamiltonian and holomorphic action of $G=U(2)$ on a compact K\"{a}hler manifold $M$, with nowhere vanishing moment map. Given an integral coadjoint orbit $\mathcal{O}$ for $G$, under transversality assumptions we shall…

Symplectic Geometry · Mathematics 2021-09-07 Roberto Paoletti

This paper is the first step in a systematic project to study examples of K\"ahler manifolds with positive holomorphic sectional curvature ($H > 0$). Previously Hitchin proved that any compact K\"ahler surface with $H>0$ must be rational…

Differential Geometry · Mathematics 2023-03-31 Bo Yang , Fangyang Zheng

We show that if a compact K\"ahler manifold admits a weighted extremal metric for the action of a torus, so too does its blowup at a relatively stable point that is fixed by both the torus action and the extremal field. This generalises…

Differential Geometry · Mathematics 2025-05-08 Michael Hallam