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We discuss the proximal game and semi-proximality in $\Psi$-spaces of almost disjoint families over an infinite countable set and $\Psi$-spaces of ladder systems on $\omega_1$. We show that a semi-proximal almost disjoint families must be…

General Topology · Mathematics 2024-12-30 Khulod Almontashery , Vinicius de Oliveira Rodrigues , Paul J. Szeptycki

Ladder operators can be useful constructs, allowing for unique insight and intuition. In fact, they have played a special role in the development of quantum mechanics and field theory. Here, we introduce a novel type of ladder operators,…

High Energy Physics - Theory · Physics 2017-09-13 Vitor Cardoso , Tsuyoshi Houri , Masashi Kimura

Motivated by importance of operator spaces contained in the set of all scalar multiples of isometries ($MI$-spaces) in a separable Hilbert space for $C^*$-algebras and E-semigroups we exhibit more properties of such spaces. For example, if…

Operator Algebras · Mathematics 2008-05-23 Waclaw Szymanski

We show that for every quasivariety K of structures (where both functions and relations are allowed) there is a semilattice S with operators such that the lattice of quasi-equational theories of K (the dual of the lattice of…

Rings and Algebras · Mathematics 2012-12-06 Kira Adaricheva , J. B. Nation

Koopman operator describes evolution of observables in the phase space, which could be used to extract characteristic dynamical features of a nonlinear system. Here, we show that it is possible to carry out interesting symbolic partitions…

Chaotic Dynamics · Physics 2020-07-23 Cong Zhang , Yueheng Lan

We study strongly continuous and locally equicontinuous families of operators on sequentially complete Hausdorff locally convex spaces. In case of Saks spaces, we relate the general notions to bi-continuity as well as equitightness. In this…

Functional Analysis · Mathematics 2026-04-16 Karsten Kruse , Christian Seifert

In this paper, we show that the lattice of C*-covers of a non-selfadjoint operator algebra is either one point or uncountable. We prove that there are non-selfadjoint operator algebras with a one-point lattice in two ways: as an explicit…

Operator Algebras · Mathematics 2026-01-09 Adam Humeniuk , Christopher Ramsey , Marcel Scherer

We transfer the theory of slack operators and sums-of-squares-criteria for lifts from convex cones to operator systems. These allow to study the following question, among others: Given an abstract operator system, is its enveloping…

Operator Algebras · Mathematics 2025-08-22 Markus Dannemüller , Tim Netzer

We give a proof of the cobordism invariance of the index of elliptic pseudodifferential operators on sigma-compact manifolds, where, in the non-compact case, the operators are assumed to be multiplication outside a compact set. We show…

K-Theory and Homology · Mathematics 2016-09-07 Catarina Carvalho

This paper is a survey of our recent work on operator algebras associated to dynamical systems that lead to classification results for the systems in terms of algebraic invariants of the operator algebras.

Operator Algebras · Mathematics 2009-04-21 K. R. Davidson , E. G. Katsoulis

We describe explicitly the algebras of degree zero operations in connective and periodic p-local complex K-theory. Operations are written uniquely in terms of certain infinite linear combinations of Adams operations, and we give formulas…

K-Theory and Homology · Mathematics 2007-05-23 Francis Clarke , Martin Crossley , Sarah Whitehouse

We study the spectral properties of Schr\"{o}dinger operators on perturbed lattices. We shall prove the non-existence or the discreteness of embedded eigenvalues, the limiting absorption principle for the resolvent, construct a spectral…

Spectral Theory · Mathematics 2024-03-26 Kazunori Ando , Hiroshi Isozaki , Hisashi Morioka

We characterize lower semi-Fredholm and Fredholm of weighted composition operators on $C(K)$ in the case when the corresponding map is an open surjection of the compact space $K$ onto itself. The obtained criterions involve the notion of…

Functional Analysis · Mathematics 2022-02-09 Arkady Kitover , Mehmet Orhon

The well known Haldane map from spin chains into the $O(3)$ non linear sigma model is generalized to the case of spin ladders. This map allows us to explain the different qualitative behaviour between even and odd ladders, exactly in the…

Condensed Matter · Physics 2008-11-26 German Sierra

We study the KMS states of the C*-algebra of a strongly connected finite k-graph. We find that there is only one 1-parameter subgroup of the gauge action that can admit a KMS state. The extreme KMS states for this preferred dynamics are…

Operator Algebras · Mathematics 2014-04-29 Astrid an Huef , Marcelo Laca , Iain Raeburn , Aidan Sims

In this paper, we construct, for a certain class of semigroup dynamical systems, two operator algebras that are universal with respect to their corresponding covariance conditions: one being self-adjoint, and another being non-self-adjoint.…

Operator Algebras · Mathematics 2020-07-10 Boyu Li

An operator space analysis of quantum stochastic cocycles is undertaken. These are cocycles with respect to an ampliated CCR flow, adapted to the associated filtration of subspaces, or subalgebras. They form a noncommutative analogue of…

Operator Algebras · Mathematics 2011-01-04 J. Martin Lindsay , Stephen J. Wills

In this article, we introduce the notions of weak boundary repre- sentation, quasi hyperrigidity and weak peak points in the non-commutative setting for operator systems in C* algebras. An analogue of Saskin theorem relating quasi…

Operator Algebras · Mathematics 2016-10-10 M. N. N. Namboodiri , S. Pramod , P. Shankar , A. K. Vijayarajan

We study non-selfadjoint operator algebras that can be entirely understood via their finite-dimensional representations. In contrast with the elementary matricial description of finite-dimensional $\mathrm{C}^*$-algebras, in the…

Operator Algebras · Mathematics 2018-06-04 Raphaël Clouâtre , Christopher Ramsey

In this paper, we study $L^1$-matrix convex sets $\{K_{n}\}$ in $*$-locally convex spaces and show that every C$^*$-ordered operator space is complete isometrically, completely isomorphic to $\{A_{0}(K_{n}, M_{n}(V))\}$ for a suitable…

Operator Algebras · Mathematics 2018-02-13 Anindya Ghatak , Anil Kumar Karn