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Let $G$ be a locally compact group. For every $G$-flow $X$, one can consider the stabilizer map $x \mapsto G_x$, from $X$ to the space $\mathrm{Sub}(G)$ of closed subgroups of $G$. This map is not continuous in general. We prove that if one…

Group Theory · Mathematics 2023-11-07 Adrien Le Boudec , Todor Tsankov

These notes give a proof of the representability of homotopy invariant K-theory in the stable homotopy category of schemes (which was announced by Voevodsky). One deduces from the proper base change theorem in stable homotopy theory of…

Algebraic Geometry · Mathematics 2013-01-18 Denis-Charles Cisinski

Consider a Hilbert space obtained as the completion of the polynomials C[z} in m-variables for which the mnonomials are orthogonal. If the commuting weighted shifts defined by the coordinate functions are essentially normal, then the same…

Operator Algebras · Mathematics 2007-05-23 Ronald G. Douglas

This paper presents algebraic methods for the study of polynomial relative invariants, when the group G formed by the symmetries and relative symmetries is a compact Lie group. We deal with the case when the subgroup H of symmetries is…

Dynamical Systems · Mathematics 2012-07-09 Patricia H. Baptistelli , Miriam Manoel

In this article, we generalize to the case of measured quantum groupoids on a finite basis some important results concerning equivariant Kasparov theory for actions of locally compact quantum groups [S. Baaj and G. Skandalis, 1989, 1993].…

Operator Algebras · Mathematics 2017-06-28 Jonathan Crespo

Traditionally, homotopy groups in $G$-equivariant stable homotopy theory have been graded over $\text{RO}(G)$, the real representation ring of $G$. It is arguably more natural to grade homotopical structures over the Picard group of the…

Algebraic Topology · Mathematics 2025-12-19 Jesse Keyes , Jordan Sawdy

In this article we formulate and prove sufficient conditions for the existence of trajectories of nonstationary periodic solutions of autonomous Hamiltonian systems in a neighbourhood of equilibria. It is worth pointing out that assumptions…

Classical Analysis and ODEs · Mathematics 2024-06-21 A. Gołębiewska , S. Rybicki

The smooth action of a compact Lie group on a compact manifold can be resolved to an iterated space, as made explicit by Pierre Albin and the second author. On the resolution the lifted action has fixed isotropy type, in an iterated sense,…

Algebraic Topology · Mathematics 2022-12-15 Panagiotis Dimakis , Richard Melrose

It is proven that in the universal splitexact equivariant algebraic $KK$-theory for algebras, the $K$-theory groups coincide with classical $K$-theory in the sense of Phillips. This partially answers a question raised by Kasparov.

K-Theory and Homology · Mathematics 2024-10-08 Bernhard Burgstaller

We provide and study an equivariant theory of group (co)homology of a group G with coefficients in a gamma-equivariant G-module A, when a separate group "gamma" acts on G and A, generalizing the classical Eilenberg-MacLane (co)homology of…

K-Theory and Homology · Mathematics 2007-05-23 H. Inassaridze

In this paper we generalize a theorem of M. Hilsum and G. Skandalis stating that the $C^*$- algebra of any foliation of non zero dimension is stable. Precisely, we show that the C*-algebra of a Lie groupoid is stable whenever the groupoid…

Operator Algebras · Mathematics 2016-06-22 Claire Debord , Georges Skandalis

The main result of this paper is an application of the topology of the space $Q(X)$ to obtain results for the cohomology of the symmetric group on $d$ letters, $\Sigma_d$, with `twisted' coefficients in various choices of Young modules and…

Representation Theory · Mathematics 2009-12-29 Frederick R. Cohen , David J. Hemmer , Daniel K. Nakano

We consider cohomological stable envelopes for a natural torus action $\mathsf{T}$ on $X=T^*Gr(k,n)$, introduced by Maulik-Okounkov. We define the $\mathbb{C}^*_\hbar$-equivariant integral of the stable envelope using equivariant…

Algebraic Geometry · Mathematics 2026-03-23 Matthew Crawford , Pavan Kartik , Reese Lance

We generalize Smirnov's formula for the elliptic stable envelopes of the Hilbert scheme of points in $\mathbb{C}^2$ to the case of affine type $A$ Nakajima quiver varieties constructed with positive stability condition. We allow for…

Algebraic Geometry · Mathematics 2021-08-05 Hunter Dinkins

We introduce a notion of $\mu$-structures which are certain locally compact group actions and prove some counterparts of results on Polish structures(introduced by Krupinski in \cite{Kru5}). Using the Haar measure of locally compact groups,…

Logic · Mathematics 2018-06-19 Junguk Lee , Michael Cohen , Phillip Wesolek

A well-known theorem of Day and Dixmier states that any uniformly bounded representation of an amenable locally compact group $G$ on a Hilbert space is similar to a unitary representation. Within the category of locally compact quantum…

Operator Algebras · Mathematics 2017-11-15 Michael Brannan , Sang-Gyun Youn

We prove a converse Lyapunov theorem for almost sure stabilizability and almost sure asymptotic stabilizability of controlled diffusions: given a stochastic system a.s. stochastic open loop stabilizable at the origin, we construct a lower…

Optimization and Control · Mathematics 2007-05-23 Annalisa Cesaroni

For a finite subgroup $\Gamma\subset \mathrm{SL}(2,\mathbb{C})$ and $n\geq 1$, we construct the (reduced scheme underlying the) Hilbert scheme of $n$ points on the Kleinian singularity $\mathbb{C}^2/\Gamma$ as a Nakajima quiver variety for…

Algebraic Geometry · Mathematics 2021-03-31 Alastair Craw , Søren Gammelgaard , Ádám Gyenge , Balázs Szendrői

In this paper we present a new proof of the homological stability of the moduli space of closed surfaces in a simply connected background space $K$, which we denote by $S_g (K)$. The homology stability of surfaces in $K$ with an arbitrary…

Algebraic Topology · Mathematics 2010-02-15 Ralph L. Cohen , Ib Madsen

We introduce a notion of ellipticity of complexes of linear pseudodifferential operators acting on sections of $A$-Hilbert bundles over smooth manifolds, $A$ being a $C^*$-algebra. We prove that the cohomology groups of an $A$-elliptic…

Operator Algebras · Mathematics 2022-08-23 Svatopluk Krýsl