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Torus manifolds are topological generalization of smooth projective toric manifolds. We compute the rational cohomology ring of a class of smooth locally standard torus manifolds whose orbit space is a connected sum of simple polytopes.

Algebraic Topology · Mathematics 2018-12-10 Soumen Sarkar , Donald Stanley

Let $G$ be a connected Lie group of rank one. In this paper the existence of free actions of group $G$ on spheres, real projective spaces and lens spaces has been studied. Most of the results have been obtained for finitistic spaces with…

Algebraic Topology · Mathematics 2013-11-28 Hemant Kumar Singh , Jaspreet Kaur , Tej Bahadur Singh

In this paper we prove that the quotient of any real or complex moment-angle complex by any closed subgroup in the naturally acting compact torus on it is equivariantly homotopy equivalent to the homotopy colimit of a certain toric diagram.…

Algebraic Topology · Mathematics 2022-06-28 Ivan Limonchenko , Grigory Solomadin

The long-standing Halperin--Carlsson conjecture (basically also known as the toral rank conjecture) states that the sum of all Betti numbers of a well-behaved space $X$ (with cohomology taken with coefficients in the cyclic group $\zz_p$ in…

Algebraic Topology · Mathematics 2012-04-30 Manuel Amann

For an action of a compact torus $T$ on a smooth compact manifold~$X$ with isolated fixed points the number $\frac{1}{2}\dim X-\dim T$ is called the complexity of the action. In this paper we study certain examples of torus actions of…

Algebraic Topology · Mathematics 2023-02-20 Anton Ayzenberg

Let $G$ be a compact connected Lie group and $K$ a closed connected subgroup. Assume that the order of any torsion element in the integral cohomology of $G$ and $K$ is invertible in a given principal ideal domain $k$. It is known that in…

Algebraic Topology · Mathematics 2021-11-24 Matthias Franz

We compute the Poincare polynomial and the cohomology algebra with rational coefficeints of the manifold M_n of real points of the moduli space of algebraic curves of genus 0 with n labeled points. This cohomology is a quadratic algebra,…

Algebraic Topology · Mathematics 2007-05-23 Pavel Etingof , Andre Henriques , Joel Kamnitzer , Eric Rains

The K-rings of non-singular complex pro jective varieties as well as quasi- toric manifolds were described in terms of generators and relations in an earlier work of the author with V. Uma. In this paper we obtain a similar description for…

Algebraic Topology · Mathematics 2007-07-12 Parameswaran Sankaran

The Koszul homology algebra of a commutative local (or graded) ring $R$ tends to reflect important information about the ring $R$ and its properties. In fact, certain classes of rings are characterized by the algebra structure on their…

Commutative Algebra · Mathematics 2021-03-16 Rachel N. Diethorn

Let $X$ be a $2n$-manifold with a locally standard action of a compact torus $T^n$. If the free part of action is trivial and proper faces of the orbit space $Q$ are acyclic, then there are three types of homology classes in $X$: (1)…

Algebraic Topology · Mathematics 2023-02-20 Anton Ayzenberg

In this work, it is shown that a simply-connected, rationally-elliptic torus orbifold is equivariantly rationally homotopy equivalent to the quotient of a product of spheres by an almost-free, linear torus action, where this torus has rank…

Differential Geometry · Mathematics 2018-10-02 Fernando Galaz-Garcia , Martin Kerin , Marco Radeschi , Michael Wiemeler

We study normal compact K\"ahler spaces whose rational cohomology ring is isomorphic to that of a complex torus. We call them rational cohomology tori. We classify, up to dimension three, those with rational singularities. We then give…

Algebraic Geometry · Mathematics 2017-03-29 Olivier Debarre , Zhi Jiang , Martí Lahoz , William F. Sawin

Assume that $G$ is a virtually torsion-free solvable group of finite rank and $A$ a $\mathbb ZG$-module whose underlying abelian group is torsion-free and has finite rank. We stipulate a condition on $A$ that ensures that $H^n(G,A)$ and…

Group Theory · Mathematics 2014-12-30 Peter Kropholler , Karl Lorensen

For any space X with the homotopy type of simply-connected, finite-type CW-complex, we construct an associative cochain algebra fls(X) whose cohomology algebra is isomorphic to that of LX, the free loop space on X. For certain X, we define…

Algebraic Topology · Mathematics 2016-09-07 Kathryn Hess

Let X be a "nice" space with an action of a torus T. We consider the Atiyah-Bredon sequence of equivariant cohomology modules arising from the filtration of X by orbit dimension. We show that a front piece of this sequence is exact if and…

Algebraic Topology · Mathematics 2014-10-24 Christopher Allday , Matthias Franz , Volker Puppe

The {\it torus manifolds} have been defined and studied by M. Masuda and T. Panov (arXiv:math.AT/0306100) who in particular describe its cohomology ring structure. In this note we shall describe the topological $K$-ring of a class of torus…

Algebraic Topology · Mathematics 2007-05-23 V. Uma

Given a torus action on a compact space X, a fundamental result of Borel and Atiyah-Segal asserts that the equivariant cohomology of X is concentrated in the fixed locus X^T, up to inverting enough Chern classes. We prove an analogue for…

Algebraic Geometry · Mathematics 2023-08-04 Adeel A. Khan , Charanya Ravi

In recent work of Kennard, Khalili Samani, and the last author, they generalize the Half-Maximal Symmetry Rank result of Wilking for torus actions on positively curved manifolds to $\mathbb{Z}_2$-tori with a fixed point. They show that if…

Differential Geometry · Mathematics 2024-11-04 Austin Bosgraaf , Christine Escher , Catherine Searle

We study the equivariant cohomology classes of torus-equivariant subvarieties of the space of matrices. For a large class of torus actions, we prove that the polynomials representing these classes (up to suitably changing signs) are…

Algebraic Geometry · Mathematics 2024-12-06 Yairon Cid-Ruiz , Yupeng Li , Jacob P. Matherne

We express the total space of a principal circle bundle over a connected sum of two manifolds in terms of the total spaces of circle bundles over each summand, provided certain conditions hold. We then apply this result to provide…

Geometric Topology · Mathematics 2025-01-29 Fernando Galaz-García , Philipp Reiser