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We extend the famous convexity theorem of Atiyah, Guillemin and Sternberg to the case of non-Hamiltonian actions. We show that the image of a generalized momentum map is a bounded polytope times a vector space. We prove that this picture is…

Symplectic Geometry · Mathematics 2007-05-23 Andrea Giacobbe

We consider Banach spaces $X$ that can be linearly lifted into their Lipschitz-free spaces $\mathcal{F}(X)$ and, for a group $G$ acting on $X$ by linear isometries, we study the possible existence of $G$-equivariant linear liftings. In…

Functional Analysis · Mathematics 2025-08-27 Valentin Ferenczi , Pedro L. Kaufmann , Eva Pernecká

We initiate the study of the norm-squared of the momentum map as a rigorous tool in infinite dimensions. In particular, we calculate the Hessian at a critical point, show that it is positive semi-definite along the complexified orbit, and…

Differential Geometry · Mathematics 2024-05-24 Tobias Diez , Tudor S. Ratiu

Functions which are equivariant or invariant under the transformations of a compact linear group $G$ acting in an euclidean space $\real^n$, can profitably be studied as functions defined in the orbit space of the group. The orbit space is…

Mathematical Physics · Physics 2009-11-10 G. Sartori , G. Valente

We extend the equivariant holomorphic Morse inequalities of circle actions to cases with torus and non-Abelian group actions on holomorphic vector bundles over Kahler manifolds and show the necessity of the Kahler condition. For torus…

dg-ga · Mathematics 2008-02-03 Siye Wu

We study parameterized elliptic systems on symmetric domains with additional system symmetries. We prove the existence of continua of nontrivial solutions bifurcating from the constant branch determined by a critical point of the potential,…

Analysis of PDEs · Mathematics 2025-10-24 Piotr Stefaniak

Let X be a CW complex with a continuous action of a topological group G. We show that if X is equivariantly formal for singular cohomology with coefficients in a field, then so are all symmetric products of X and in fact all its…

Algebraic Topology · Mathematics 2019-08-15 Matthias Franz

This paper concerns the action of linear symplectomorphisms on linear symplectic forms by conjugation in even dimensions. We prove that pfaffian and $-\frac{1}{2}\operatorname{tr}(JA)$ (sum function) of $A$ are invariants on the action. We…

Symplectic Geometry · Mathematics 2022-12-19 Luchen Shi , Sunay Joshi , Ritwick Bhargava

Let $G$ be a semisimple Lie group acting on a space $X$, let $\mu$ be a compactly supported measure on $G$, and let $A$ be a strongly irreducible linear cocycle over the action of $G$. We then have a random walk on $X$, and let $T$ be the…

Dynamical Systems · Mathematics 2019-01-09 Alex Eskin , Carlos Matheus

This article is a survey of recent work of the authors developing a new approach to quantization based on the equivariance with respect to some Lie group of symmetries. Examples are provided by conformal and projective differential…

Differential Geometry · Mathematics 2007-05-23 C. Duval , P. Lecomte , V. Ovsienko

In this paper, we endow the space of continuous translation invariant valuation on convex sets generated by mixed volumes coupled with a suitable Radon measure on tuples of convex bodies with two appropriate norms. This enables us to…

Differential Geometry · Mathematics 2019-03-26 Nguyen-Bac Dang , Jian Xiao

We introduce a twisted action of the equivariant cohomology of the singleton $H_R^\bullet({\rm pt},\Bbbk)$ on the equivarinat cohomology $H_L^\bullet(X,\Bbbk)$ of an $L$-space $X$. Considering this actions as a right action,…

Algebraic Topology · Mathematics 2024-11-20 Vladimir Shchigolev

We construct all possible Hamiltonian torus actions for which all the non-empty reduced spaces are two dimensional (and not single points) and the manifold is connected and compact, or, more generally, the moment map is proper as a map to a…

Symplectic Geometry · Mathematics 2014-11-11 Yael Karshon , Susan Tolman

We establish an equivariant generalization of the Novikov inequalities which allow to estimate the topology of the set of critical points of a closed basic invariant form by means of twisted equivariant cohomology of the manifold. We apply…

dg-ga · Mathematics 2008-02-03 M. Braverman , M. Farber

We consider entire solutions to $\mathcal{L}u=f(u)$ in $\mathbb R^2$, where $\mathcal L$ is a nonlocal operator with translation invariant, even and compactly supported kernel $K$. Under different assumptions on the operator $\mathcal L$,…

Analysis of PDEs · Mathematics 2016-01-22 Francois Hamel , Xavier Ros-Oton , Yannick Sire , Enrico Valdinoci

We consider left-invariant optimal control problems on connected Lie groups such that generic stabilizer of the coadjoint action is connected and has dimension not more than 1. We introduce a construction for symmetries of the exponential…

Optimization and Control · Mathematics 2020-06-02 A. V. Podobryaev

In this paper, we investigate the asymptotic behaviors of the solutions of nonlinear dynamic systems nearby an equilibrium point, when the nominal parts are subject to non necessarily small perturbations. We show that, under some estimates…

Dynamical Systems · Mathematics 2020-08-07 Mondher Benjemaa , Wided Gouadri , Mohamed Ali Hammami

We give a systematic presentation of the stability theory in the non-algebraic Kaehlerian geometry. We introduce the concept of "energy complete Hamiltonian action". To an energy complete Hamiltonian action of a reductive group G on a…

Complex Variables · Mathematics 2007-05-23 Andrei Teleman

This paper is a continuations of the project initiated in the book string topology for stacks. We construct string operations on the SO(2)-equivariant homology of the (free) loop space $L(X)$ of an oriented differentiable stack $X$ and show…

Algebraic Topology · Mathematics 2016-01-13 Gregory Ginot , Behrang Noohi

We study isometric actions of compact Lie groups on complete orientable positively curved $n$-manifolds whose orbit spaces have non-empty boundary in the sense of Alexandrov geometry. In particular, we classify quotients of the unit sphere…

Differential Geometry · Mathematics 2024-02-23 Claudio Gorodski , Andreas Kollross , Burkhard Wilking