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We consider Picard surfaces, locally symmetric varieties $S_{\Gamma}$ attached to the Lie group SU(2,1), and we construct explicit differential forms on $S_{\Gamma}$ representing Eisenstein classes, i.e. cohomology classes restricting…

Number Theory · Mathematics 2024-02-02 Jitendra Bajpai , Mattia Cavicchi

We adapt algorithms for resolving the singularities of complex algebraic varieties to prove that the natural map of homology theories from complex bordism to the bordism theory of complex derived orbifolds splits. In equivariant stable…

Algebraic Topology · Mathematics 2025-04-25 Mohammed Abouzaid , Shaoyun Bai

In this note we introduce the notion of a smooth structure on a conical pseudomanifold $M$ in terms of $C^\infty$-rings of smooth functions on $M$. For a finitely generated smooth structure $C^\infty (M)$ we introduce the notion of the Nash…

Differential Geometry · Mathematics 2014-07-18 Hong Van Le , Petr Somberg , Jiri Vanzura

We study the following generalization of singularity categories. Let X be a quasi-projective Gorenstein scheme with isolated singularities and A a non-commutative resolution of singularities of X in the sense of Van den Bergh. We introduce…

Representation Theory · Mathematics 2017-09-15 Martin Kalck

We investigate static, spherically symmetric solutions in gravitational theories which have limited curvature invariants, aiming to remove the singularity in the Schwarzschild space-time. We find that if we only limit the Gauss-Bonnet term…

General Relativity and Quantum Cosmology · Physics 2018-07-25 Daisuke Yoshida , Robert H. Brandenberger

We present a geometric realization of the duality between skeleta in $T^*\mathbb P^n$ and collars of local surfaces. Such duality is predicted by combining two auxiliary types of duality: on one side, symplectic duality between $T^*\mathbb…

Symplectic Geometry · Mathematics 2024-01-09 Edoardo Ballico , Elizabeth Gasparim , Francisco Rubilar , Bruno Suzuki

We consider principal bundles as generalized morphisms between topological groupoids. In the category of these generalized morphisms two topological groupoids are isomorphic if and only if they are Morita equivalent. We show that the fibers…

Differential Geometry · Mathematics 2007-05-23 Janez Mrcun

The local Euler obstructions and the Euler characteristics of linear sections with all hyperplanes on a stratified projective variety are key geometric invariants in the study of singularity theory. Despite their importance, in general it…

Algebraic Geometry · Mathematics 2021-05-11 Xiping Zhang

We study collections of exact Lagrangian submanifolds respecting some uniform Riemannian bounds, which we equip with a metric naturally arising in symplectic topology (e.g. the Lagrangian Hofer metric or the spectral metric). We exhibit…

Symplectic Geometry · Mathematics 2024-07-17 Jean-Philippe Chassé

Isolated horizons that admit the Hopf bundle structure $H\rightarrow S_2$ are investigated, however the null direction is allowed not to be tangent to the bundle fibres. The geometry of such horizons is characterised by data set on a…

General Relativity and Quantum Cosmology · Physics 2023-12-01 Denis Dobkowski-Ryłko , Jerzy Lewandowski , Maciej Ossowski

We study vector bundles over Lie groupoids, known as VB-groupoids, and their induced geometric objects over differentiable stacks. We establish a fundamental theorem that characterizes VB-Morita maps in terms of fiber and basic data, and…

Differential Geometry · Mathematics 2020-07-27 Matias del Hoyo , Cristian Ortiz

Let (W,S) be a Coxeter system. We introduce the boolean complex of involutions of W which is an analogue of the boolean complex of W studied by Ragnarsson and Tenner. By applying discrete Morse theory, we determine the homotopy type of the…

Combinatorics · Mathematics 2021-09-14 Axel Hultman , Vincent Umutabazi

Logarithmic and $b$-tangent bundles provide a versatile framework for addressing singularities in geometry. Introduced by Deligne and Melrose, these modified bundles resolve singularities by reframing singular vector fields as well-behaved…

Differential Geometry · Mathematics 2025-02-27 Eva Miranda , Pablo Nicolás

We obtain a class of locally symmetric Kaehler Einstein structures on the cotangent bundle of a Riemannian manifold of negative sectional curvature. Similar results are obtained in the case of a Riemannian manifold of positive sectional…

Differential Geometry · Mathematics 2007-05-23 D. D. Porosniuc

We investigate the structure of smooth holomorphic foliations with numerically flat tangent bundles on compact K\"ahler manifolds. Extending earlier results on non-uniruled projective manifolds by the second and fourth authors, we show that…

Algebraic Geometry · Mathematics 2024-11-14 Stéphane Druel , Jorge Vitório Pereira , Brent Pym , Frédéric Touzet

We set up a topological framework for degenerations of symplectic manifolds into singular spaces paying a special attention to the behavior of Lagrangian manifolds and their (holomorphic) membranes. We show that degenerations into singular…

Symplectic Geometry · Mathematics 2023-03-14 Sergey Galkin , Grigory Mikhalkin

We discuss the structure of shock singularities of the Burgers-Hopf hierarchy. It is shown that the set of singular solutions defines a stratification of the affine space of the flow parameters in the hierarchy. The stratification is…

Exactly Solvable and Integrable Systems · Physics 2009-11-07 Y. Kodama , B. G. Konopelchenko

This is a part of our joint program. The purpose of this paper is to study smooth toroidal compactifications of Siegel varieties and their applications, we also try to understand the K\"ahler-Einstein metrics on Siegel varieties through the…

Algebraic Geometry · Mathematics 2014-05-20 Shing-Tung Yau , Yi Zhang

We study Weinstein 4-manifolds which admit Lagrangian skeleta given by attaching disks to a surface along a collection of simple closed curves. In terms of the curves describing one such skeleton, we describe surgeries that preserve the…

Symplectic Geometry · Mathematics 2016-03-25 Vivek Shende , David Treumann , Harold Williams

We define a class of finite-dimensional Jacobian algebras, which are called (simple) polygon-tree algebras, as a generalization of cluster-tilted algebras of type $\D$. They are $2$-CY-tilted algebras. Using a suitable process of mutations…

Representation Theory · Mathematics 2016-04-01 Ming Lu