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We study topologization of the semigroup $\mathscr{O\!\!I}\!_n(L)$ of finite partial order isomorphisms of a bounded rank of an infinite linear ordered set $(L,\leqslant)$. In particular we show that every $T_1$ left-topological…

Group Theory · Mathematics 2025-12-01 Oleg Gutik , Maksym Shchypel

This paper is concerned with emptyness of the essential spectrum, or equivalently compactness of the semigroup, for perturbations of selfadjoint operators that are bounded below (on an L^2-space). For perturbations by a (nonnegative)…

Spectral Theory · Mathematics 2010-03-24 Daniel Lenz , Peter Stollmann , Daniel Wingert

We reveal new aspects of the structure of Hilbert space $C_0$-semigroups $\mathcal T = (T(t))_{t\ge 0}$ similar to semigroups of contractions. In particular, we prove that $\mathcal T$ is similar to a semigroup of contractions if and only…

Functional Analysis · Mathematics 2025-09-04 J. Oliva-Maza , Y. Tomilov

Let $S$ be a semitopological semigroup and $\mathcal{CB}(S)$ denotes the $C^*$-algebra of all bounded complex valued continuous functions on $S$ with uniform norm. A function $f\in \mathcal{CB}(S)$ is left multiplicative \linebreak…

Functional Analysis · Mathematics 2013-02-14 M. Akbari Tootkaboni

This paper provides a complete characterization of quasicontractive groups and analytic $C_0$-semigroups on Hardy and Dirichlet space on the unit disc with a prescribed generator of the form $Af=Gf'$. In the analytic case we also give a…

Functional Analysis · Mathematics 2016-01-13 C. Avicou , I. Chalendar , J. R. Partington

In this paper we consider the existence of dense embeddings of Limit groups in locally compact groups generalizing earlier work of Breuillard, Gelander, Souto and Storm [GBSS] where surface groups were considered. Our main results are…

Group Theory · Mathematics 2012-04-17 Jonathan Barlev , Tsachik Gelander

We define a class of transversal slices in spaces which are quasi-Poisson for the action of a complex semisimple group G. This is a multiplicative analogue of Whittaker reduction. One example is the multiplicative universal centralizer of…

Representation Theory · Mathematics 2022-09-19 Ana Balibanu

We define and study a family of partitions of the wonderful compactification \bar{G} of a semi-simple algebraic group G of adjoint type. The partitions are obtained from subgroups of G \times G associated to triples (A_1, A_2, a), where A_1…

Representation Theory · Mathematics 2007-05-23 Jiang-Hua Lu , Milen Yakimov

For a semibounded sesquilinear form ${\mathfrak t}$ in a Hilbert space ${\mathfrak H}$ there exists a representing map $Q$ from ${\mathfrak H}$ to another Hilbert space ${\mathfrak K}$, such that ${\mathfrak t}[\varphi, \psi]-c(\varphi,…

Functional Analysis · Mathematics 2024-01-02 Seppo Hassi , Henk de Snoo

In this paper, we consider the diagonal action of a connected semisimple group of adjoint type on its wonderful compactification. We show that the semi-stable locus is a union of the $G$-stable pieces and we calculate the geometric…

Algebraic Geometry · Mathematics 2009-07-03 Xuhua He , Jason Starr

This paper has two goals: to present some new results that are necessary for further study and applications of quasi-linear functionals, and, by combining known and new results, to serve as a convenient single source for anyone interested…

Functional Analysis · Mathematics 2019-02-12 Svetlana V. Butler

The semidirect product $\mathbb{G}=\mathbb{L}\rtimes \mathbb{K}$ attached to a compact-group action on a connected, simply-connected solvable Lie group has a dense set of compact elements precisely when the $s\in \mathbb{K}$ operating on…

Group Theory · Mathematics 2025-07-08 Alexandru Chirvasitu

We prove collective versions of semi-duality theorems for sets of almost (limitedly, order) L-weakly compact operators.

Functional Analysis · Mathematics 2024-10-29 Safak Alpay , Eduard Emelyanov , Svetlana Gorokhova

Given a quasi-reductive group $G$ over a local field $k$, using Berkovich geometry, we exhibit a family of $G(k)$-equivariant compactifications of the Bruhat-Tits building $\mathcal B(G, k)$, constructed and investigated by Solleveld and…

Group Theory · Mathematics 2022-06-13 Dorian Chanfi

We introduce a general framework, based on \'etale topological categories, for studying discrete restriction semigroups and their algebras. Generalizing Paterson's universal groupoid of an inverse semigroup, we define the universal category…

Rings and Algebras · Mathematics 2025-11-07 Ganna Kudryavtseva

In this paper we study the separately continuous actions of semitopological monoids on pseudocompact spaces. The main aim of this paper is to generalize Lawson's results to some class of pseudocompact spaces. Also, we introduce a concept of…

General Topology · Mathematics 2023-11-14 Alexander V. Osipov , Konstantin Kazachenko

Let $S$ be a semitopological semigroup. The $wap-$ compactification of semigroup S, is a compact semitopological semigroup with certain universal properties relative to the original semigroup, and the $Lmc-$ compactification of semigroup…

Functional Analysis · Mathematics 2013-02-14 M. Akbari Tootkaboni

Let F be a global field, and let S be a finite set of places of F containing all archimedean places. Consider the product X of the symmetric spaces and Bruhat-Tits buildings for PGL_d of the completions of F at archimedean and…

Number Theory · Mathematics 2016-12-12 Takako Fukaya , Kazuya Kato , Romyar Sharifi

This is the third paper of a series relating the equivariant twisted $K$-theory of a compact Lie group $G$ to the ``Verlinde space'' of isomorphism classes of projective lowest-weight representations of the loop groups. Here, we treat…

Algebraic Topology · Mathematics 2007-05-23 Daniel S. Freed , Michael J. Hopkins , Constantin Teleman

This paper is a continuation of [5]. Using the root categories, we define the compact real forms of the complex semisimple Lie algebras, and maximal compact subgroups of the Chevalley groups over $\mathbb{C}$. In [7], Lusztig used the…

Representation Theory · Mathematics 2026-02-26 Buyan Li , Jie Xiao