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Related papers: On the mean Euler characteristic of contact manifo…

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The aim of the paper is three-fold. We begin by proving a formula, both global and local versions, relating the number of periodic orbits of an iterated map and the Lefschetz numbers, or indices in the local case, of its iterations. This…

Symplectic Geometry · Mathematics 2013-11-05 Viktor L. Ginzburg , Yusuf Gören

We prove that the mean Euler characteristic of a Gorenstein toric contact manifold, i.e. a good toric contact manifold with zero first Chern class, is equal to half the normalized volume of the corresponding toric diagram and give some…

Symplectic Geometry · Mathematics 2020-02-12 Miguel Abreu , Leonardo Macarini

We examine open books with powers of fibered Dehn twists as monodromy. The resulting contact manifolds can be thought of as Boothby-Wang orbibundles over symplectic orbifolds. Using the mean Euler characteristic of equivariant symplectic…

Symplectic Geometry · Mathematics 2018-11-08 River Chiang , Fan Ding , Otto van Koert

In a closed manifold of positive dimension $n$, we estimate the expected volume and Euler characteristic for random submanifolds of codimension $r\in \{1,...,n\}$ in two different settings. On one hand, we consider a closed Riemannian…

Metric Geometry · Mathematics 2016-02-26 Thomas Letendre

Indices of singular points of a vector field or of a 1-form on a smooth manifold are closely related with the Euler characteristic through the classical Poincar\'e--Hopf theorem. Generalized Euler characteristics (additive topological…

Geometric Topology · Mathematics 2019-03-19 S. M. Gusein-Zade

Manifolds admitting positive sectional curvature are conjectured to have rigid homotopical structure and, in particular, comparatively small Euler charateristics. In this article, we obtain upper bounds for the Euler characteristic of a…

Differential Geometry · Mathematics 2014-07-22 Manuel Amann , Lee Kennard

The translative intersection formula of integral geometry yields an expression for the mean Euler characteristic of a stationary random closed set intersected with a fixed observation window. We formulate this result in the setting of sets…

Probability · Mathematics 2021-04-20 Jan Rataj

We study closed manifolds with almost nonnegative curvature operator and address a question of Herrmann--Sebastian--Tuschmann concerning the sign of their Euler characteristic. Our main result shows that if a closed $2n$-dimensional…

Differential Geometry · Mathematics 2026-03-26 Jing-Bin Cai

In this note we show that the mean Euler characteristic of equivariant symplectic homology is an effective obstruction against the existence of displaceable exact contact embeddings. As an application we show that certain Brieskorn…

Symplectic Geometry · Mathematics 2015-01-14 Urs Frauenfelder , Felix Schlenk , Otto van Koert

We show that whenever a Hamiltonian diffeomorphism or a Reeb flow has a finite number of periodic orbits, the mean indices of these orbits must satisfy a resonance relation, provided that the ambient manifold meets some natural…

Symplectic Geometry · Mathematics 2009-07-10 Viktor L. Ginzburg , Ely Kerman

We discuss the universal orbifold Euler characteristic and generalized orbifold Euler characteristics corresponding to finitely generated groups $A$ (the $A$-Euler characteristics). We show that the collection of all $A$-Euler…

Algebraic Geometry · Mathematics 2024-05-15 Sabir M. Gusein-Zade , Ignacio Luengo , Alejandro Melle-Hernández , Antonio Viruel

We prove that the minimal Euler characteristic of a closed symplectic four-manifold with given fundamental group is often much larger than the minimal Euler characteristic of almost complex closed four-manifolds with the same fundamental…

Geometric Topology · Mathematics 2007-05-23 D. Kotschick

In this note, we consider contractible loops of contactomorphisms that are positive over some non-empty closed subset of a contact manifold. Such closed subsets are called immaterial. We argue that the complement of a Reeb-invariant…

Symplectic Geometry · Mathematics 2026-05-20 Igor Uljarević

A theorem due to D. Bernstein states that Euler characteristic of a hypersurface defined by a polynomial f in (C\{0})^n is equal (upto a sign) to n! times volume of the Newton polyhedron of f. This result is related to algebaric torus…

Algebraic Geometry · Mathematics 2007-05-23 Kiumars Kaveh

We show that an overtwisted contact structure on a closed, oriented 3-manifold can be defined by a contact form having a Bott-integrable Reeb flow if and only if the Poincar\'e dual of its Euler class is represented by a graph link.

Symplectic Geometry · Mathematics 2026-03-31 Hansjörg Geiges , Jakob Hedicke , Murat Sağlam

In this paper, we show that the Euler characteristic of an even dimensional closed projectively flat manifold is equal to the total measure which is induced from a probability Borel measure on RP^n invariant under the holonomy action, and…

Geometric Topology · Mathematics 2007-05-23 Kyeonghee Jo , Hyuk Kim

We develop the details of a surgery theory for contact manifolds of arbitrary dimension via convex structures, extending the 3-dimensional theory developed by Giroux. The theory is analogous to that of Weinstein manifolds in symplectic…

Symplectic Geometry · Mathematics 2019-05-29 Kevin Sackel

The Euler characteristic of a finite category is defined and shown to be compatible with Euler characteristics of other types of object, including orbifolds. A formula for the cardinality of the colimit of a diagram of sets is proved,…

Category Theory · Mathematics 2010-02-04 Tom Leinster

In this short note, we provide a calculation of the Euler characteristic of a finite homotopy colimit of finite cell complexes, which depends only on the Euler characteristics of each space and resembles Mobius inversion. Versions of the…

Algebraic Topology · Mathematics 2018-11-07 John D. Berman

In this article we mainly aim to know what kind of asymptotic behavior of typical orbits can display. For example, we show in any transitive system, the emprical measures of a typical orbit can cover all emprical measures of dense orbits…

Dynamical Systems · Mathematics 2021-11-15 Xiaobo Hou , Wanshan Lin , Xueting Tian
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